There's a new Unearthed Arcana feature in town, and it's kind of a double feature: both prestige classes in concept and the Rune Scribe prestige class in particular. As I start this article, I haven't even read the whole thing yet - the Rune Scribe is a dense read, since it has a freestanding "spell list" - so we'll experience this together.
Now, if you played 3.x at all, you'll recognize several salient points of how 5e's Prestige Classes work. If you're anything at all like me or most of the 3.x players I know, you also regard Prestige Classes with a lot of skepticism, for several reasons:
they put players in a position of having to plan their level progression well in advance just to satisfy prerequisites that, at times, had only the vaguest connection to class theme;
game balance was an open question, especially when a character combined two or more core classes and two or more prestige classes to cherry-pick abilities; and
even without taking third-party content into account, there were so many prestige classes that players experienced pressure toward system mastery and the metagame, even contrary to roleplaying concerns.
(If you liked prestige classes in concept or in specific, you don't have to justify yourself to me. We can disagree amiably.)
Right off the bat, then, I like the text's emphasis on treating prestige classes as the in-world organizations and concepts that they are, pushing interaction with NPCs. Yes, this means that a jerk DM can screw you out of your build plan. Don't play with jerk DMs (and don't be a jerk DM)... but also respect the game's content and engage with it. Don't put your own agenda above everyone else's (no matter what your role in a game is). But I digress.
The normal rules frame of prestige class prerequisites is a level requirement (always at least 3rd level; the Rune Scribe requires 5th level), at least one ability score requirement (this parallels ability score requirements for multiclassing, but... man, I do not like it, see below), and the completion of a specified deed (there are good sides and bad sides to gating advancement by game content).
This isn't particularly controversial. If there weren't a level requirement, this would just be a base class, and we would wonder why it had a five-level progression rather than a twenty-level progression (other than the fact that it's a UA playtest and all the UA playtests have been five-level progressions lately - that is a little joke). The only issue here is that a lot of games don't run long enough for players to reach both the prerequisite level and the top level of the prestige class, which can be really frustrating - so I hope we won't see a ton of "must be 15th level to enter."
Ability Score Requirement
This requirement, on the other hand, really gets up my nose. It separates the decision to meet qualifications from the decision to enter the prestige class by some number of levels. For example, the Rune Scribe requires Dex 13 and Int 13. Now, the class thematically targets wizards and knowledge clerics anyway - people with a pre-existing incentive to have a good Int score. This Dex business, though? Sure, the wizard might have a good Dex score for AC... but I don't think it's at all unreasonable to imagine a wizard or knowledge cleric starting with a 10 Dex, not specifically planning around being a Rune Scribe. Congratulations, 8th level is now your minimum entry point for this prestige class, and you had to spend a lot of your advancement potential just meeting this prerequisite that does nothing else for you within the class. Now, a generous DM would probably let a player rearrange ability score points, possibly as a limited option within the Training downtime activity.
Completion of a Deed
I'm on the record as liking achievement-based advancement, but there are meaningful game-running challenges around requiring that players complete a particular deed in order to qualify for a prestige class. It amounts to the player saying, "Also, weave this thing in that I have just introduced, and do it by the time I hit a particular level, or else my progression is stuck." It's good for players to make choices that guide the action, but adding content on a player's timeline really adds to the pressure on the DM - and (probably) all the worse on the big adventure paths that are WotC's core content stream, and which they intend as a unified player experience of D&D.
On the other hand, without some completion of a deed, I'm not sure how prestige enters into it. It's complicated. Spelling out advice to DMs allowing players to occasionally respend character levels might help - it trades a certain amount of narrative consistency for a lot of gameplay quality-of-life. I like that the text sets expectations on "you may have to complete additional deeds as you advance," giving the DM cover for hanging more story on the prestige class, rather than just coming across as the asshole putting more hurdles in the PCs' way.
The rules for prestige classes otherwise behave like the existing multiclassing rules. Prestige classes will spell out the amount of spellcasting that they contribute to your multiclass spellcasting progression - for example, the Rune Scribe has an internal spellcasting mechanic or grants 1:1 spellcasting advancement.
There's just enough explaining going on in this document that for a bit there I thought the rune scribe slots were a progression disconnected from your core spellcasting progression. This whole class makes a little more sense to me now that I realize that's not what it's saying, and I now understand that it's not a complete waste for people who don't already have spellcasting to take this class.
Of course, as with other multiclassing, that takes the form of your spell slots progressing, even if your spells known do not - which means you cast your spells with higher-level slots, but a wizard who takes four or five levels of Rune Scribe is never casting meteor swarm, unless the DM makes that possible through post-20th-level advancement.
That's it for prestige class rules. On the whole they're tolerable with DM oversight and a certain generosity of approach. I don't love them, but I don't really have any improvements to offer other than scrapping the ability score requirement, or setting it as an A or B requirement. Maybe you can make up for a lack of Dex with an insight that surpasses academic knowledge (Wis 15 in place of Dex 13, say). Also, just based on the story elements of entering an organization that has secret knowledge, Training downtime in order to advance should probably be enforced.
The Rune Scribe
This class is about mastering the fundamental magic of creation. I like that it is giantish magic, because I really like 5e's giant lore (taken from earlier editions, but presented very clearly in the Monster Manual). As mentioned before, it requires Dex 13, Int 13, and 5th level; it further requires Arcana skill proficiency, finding a rune, and delivering it to someone who is already a rune scribe. Given the "fundamental magic of creation" bit, I would have thought Religion was just as applicable, but whatever.
The writeup buries the lead on this just a bit, but runes are a new type of magic item. A big part of this class seems to hang on being better at using runes than people who don't have this prestige class.
Rune Lore is a baseline ability that opens up the secret applications of runes to you. Glancing ahead a bit, the runes all have three simple (open to all characters) properties and three complex (rune scribe only) properties, so this seems like a pretty big deal. I haven't studied the runes in depth yet - we'll get to that.
Runic Magic is the class ability that grants a spell slot progression. The number of slots progresses in the same way as any other spellcasting progression, but the class has only five levels, so you naturally stop at 3rd level spells, unless you're already a spellcaster.
Here I note that I am very glad they gave all classes, including spellcasters, class features other than just more-and-better spell slots, or this would be an empty tradeoff like it was for 3.x prestige classes.
The complex powers of runes require spell slots to function, so in one way they're like narrow grimoires that also soak up attunement slots, while further granting cool powers. This is getting more interesting.
Runic Discovery is a way to let the character choose runes, rather than having to find them as treasure. Runic discovery occurs three times in the rune scribe's five-level progression, so make it count (and also hope for runes as loot). Considering how much Mearls and his ill-favored band of desperadoes have talked about the game not depending on magic items, this is a good cover to make sure a class solely about using a particular type of magic item remains playable. The downside to hanging the class on attunement to runes is that once you've invested five levels in a prestige class, you feel weird about using your three precious attunements for anything other than runes, and you might very well stop taking interest in loot altogether.
Living Runes are this class's answer to Ability Score Increases - instead of picking something once and being done with it, you basically gain two ability score points that you can move around at the end of any long rest, and cannot spend on a feat instead. This is weird, and I'm not sure that recalculating things at the end of any long rest is going to go well at the table. I'm sure these ability score points adhere to the standard cap at 20, though the writeup could stand to call that out.
Rune Mastery is a nod to that problem of running out of attunements that I mentioned, granting a bonus attunement that can only be used for a rune. It helps, though runes do enough different things that I suspect most rune scribes will just attune a fourth rune.
So... this class writeup tells us nothing about how this class plays, even less than the wizard writeup tells you how a wizard plays without reading their spell list. Fortunately, the Rune Magic section of the document is next.
Okay, so the proper name of these magic items is master runes. (The document's terminology usage between rune and master rune is confusing.) They range in rarity from rare to legendary - there are no common or uncommon runes. Which means you must give a Rare magic item to a 5th level character, or you're barring her from this prestige class. I'm a bit dubious on this point. In this playtest, they're showing off four runes: ild, stein, vind, and kalt, or fire, stone, wind, and cold, respectively.
This rune's simple properties are straightforward - it ignites and extinguishes fires and grants cold resistance. Cold resistance might be worth an attunement slot; for most characters, the other two powers won't carry the argument. For rune scribes, it adds:
a touch-range attack "spell" that costs a spell slot to deal damage... but has no spell attack roll or saving throw. It's not a huge amount of damage, but there's no way to avoid it short of resistance or immunity. This is pretty potent, but expensive for its damage output.
a magic weapon-style effect that also changes the weapon's damage to fire. The really good side of this is the 24-hour duration. It's completely plausible to activate this power, take a long rest, switch out your runic attunement, and still use your flame brand weapon.
and a passive ability called flame stoker that lets you reroll all fire damage dice and take the higher result. Pretty good; hard for me to judge without more math than I'm going to do right now.
What we have here is a case of a linguistically reasonable word that either does not quite pass a playground test (beer magic, ha ha) or is a little on the nose for dwarven rune scribes. On the other hand, even its simple powers are ridiculously good.
Advantage on checks and saving throws against forced movement and a passive chance to stop the movement of any creature that approaches you. (Congratulations on griefing your party!) Just remembering to use the second part of this effect sounds like a lot of mental load and I would suggest cutting it down to a per-short-rest reaction power.
Immunity to petrification. Doesn't come up much, but immunity is always desirable.
Stone's secrets is not super easy to use well, though it can tell you if someone's within 30 feet of the other side of a door. It can check for invisible creatures, but it costs your action to use, so that's a bit inconvenient.
The complex powers are also better than ild:
the earth-powered weapon ability, called crushing brand, is mostly better than flame brand, as it ignores resistance or immunity to bludgeoning damage rather than shifting type to work around resistance or immunity, and tacks on knocking your target down if you roll the maximum on the damage dice. (This is a case where rolling multiple damage dice is a huge disadvantage, and they should probably clean up the language to avoid that.)
meld into stone as a bonus action, once per short rest. Quite good.
a damage-plus-knockdown chance attack "spell," with a saving throw. The damage is not bad. The weird thing is that the saving throw DC for the knockdown scales by the spell slot expended - I can't think of anywhere else I've seen 5e use that mechanic.
The rune of wind does pretty well for itself, though I think not as mighty as stein.
The first power is an immunity to both suffocation and drowning, and advantage on saving throws where holding your breath could help (inhaled toxins and so on).
The second and third power both deal with movement - short-distance flight as we've seen in subclasses and such, where you fall if you're not on solid ground at the end of your turn (wuxia style, except that it costs your action for the round), and a feather fall-like effect as a reaction.
These are quite good, though I'm surprised the flight power is as limited as it is. The complex powers are a bigger deal:
Howling brand is for ranged weapons, and in combination with range-increasing feats and such, you're shooting people hilariously far away without so much as disadvantage. Inability to see the target due to curvature of the earth (or just Perception check DCs) may be your main limiter. Because of standard fight distances, I'm not sure this is all that great.
Shrieking bolt is a lot like stein's damage power, but it's a 10-foot push rather than knockdown.
Considering that all of the runes' bolt powers are touch-range, this is the obvious go-to for people who started out life as wizards or lore bards, because it pushes the enemy off of you and lets you run away without opportunity attacks taking place. Indomitable stand is a close second here, aside from all of its inconvenience.
Wind walker allows you to levitate as a bonus action. It's nice, but in most cases levitate seems pretty limited. Good for getting you out of the thick of a fight, at least.
The rune of ice is just goddamn amazing.
Frigid touch lets you build ice bridges across anything you can freeze. I don't know about y'all, but I played a metric ton of Arkham City, and I have a real good idea of how useful this could be in solving elaborate puzzles, if the DM has the level-design chops to create them.
Frost friend grants resistance to fire. Always useful.
Icy mantle is kind of insane. As an action, you place an effect on someone that negates the next bludgeoning, piercing, or slashing hit that they take. I can envision situations in which this might be a good choice to use every round to protect the team's defender. As written, there's no reason that every member of the party wouldn't start every fight with an icy mantle active, but I'm pretty sure that's more than intended.
And that's just the simple powers! The complex ones are... mostly not that big of a deal.
Freezing bolt is the direct damage-plus-effect power for kalt, and its effect is a one-round snare (that is, reduces the target's speed to 0 on a failed saving throw). This is quite good, and a devastating setup for someone else in the party to drop some of the awful damaging zone effects, especially the ones found in the Elemental Evil Player's Companion.
Much like flame brand, ice brand isn't great. Resistance or immunity to B/P/S damage is actually not all that common, especially taking into account the probability that the PC has a magic weapon. Resistance or immunity to fire and cold, on the other hand, are quite common.
Winter's howl gives you a free sleet storm once per short or long rest. It's a third-level spell, it's fine... just very situational in its uses.
Okay, so we have a weird variant caster that would fit really well with the themes of several different classes - bard, Knowledge cleric, Circle of the Land druid, eldritch knight fighter, and wizard all feel right to me. Even characters without any spellcasting, but with the Arcana skill picked up from a Background or feat expenditure, could get good mileage out of this class. It's a sufficiently specific class flavor that it feels to me like someone who mostly studies whatever other topic decided to divert into studying runes for awhile - something like that could definitely happen in Dust to Dust, after all (and does).
The four runes they've presented seem pretty questionable on the balance side. In principle I'm interested in the gameplay of cycling between runes during a short rest, effectively rebuilding your "spell list" (some of which are passive powers, and others of which don't cost a spell slot) on short notice. It's not quite the rapid-fire stance-dancing of the playtest Mystic, but it's pretty cool all the same. (If I recall correctly, the class of previous editions most similar to the Rune Scribe is actually the Binder from 3.5. That's... interesting.)
If all Rare runes are about the same, a 5th-level rune scribe has 6-24 items on her "spell list." It's possible that Very Rare and Legendary runes push this higher, or that they just have greater power. Balancing runes can be a whole new area of third-party content, though probably not one that anyone will go all that deep on for a good while. (I'll probably write up a few.)
Taken together... I actually don't have much of a problem with this. I think the ability score prerequisites don't serve all that much purpose. I think reworking more prereqs as "either A, or more difficult B, or both C and D" would protect theme while reducing the system mastery and build-planning necessary for play.
The Rune Scribe probably doesn't experience a huge gameplay shift from whatever class(es) the player started in - they just pick up a pretty involved bag of weird tricks, especially defensive features. Most of their serious damage output still comes from their base class, even if that's just by boosting their bolt effects with spell slots of higher levels. If I were creating a Dust to Dust hack of D&D, I would absolutely do something with this... but I'm not sure I wouldn't rework it into a base class.
I leave you with the best song about what my headcanon has decided are neo-medieval scribes that I have ever heard.