My thoughts turned back to the Ranger class recently, as I'm working toward the release of a PDF of ranger archetypes through the OGL. I've written two so far, the Lantern-bearer and the Stormcloak, and coming up with a third seemed fitting. At first I was thinking of doing something themed around thorns, sort of a more stabby version of the 2e Greenwood Ranger kit. I will probably come back to that idea at some point, but once I got to talking to Stands-in-Fire about what I would do with it, he mentioned traps that the ranger deploys in combat, and the Survivalist archetype fell out.
Survivalist (Ranger Archetype)
A Survivalist ranger looks to cunning traps as a first line of defense and the best way to turn an enemy's aggression into a deadly mistake. They weave magic into their traps to make them all the more devastating. Many survivalist rangers have a reputation for eccentricity or paranoia, but in truth this is common to all who tinker with small, deadly pieces of metal. Just look at the rock gnomes and tinkering goblins.
The DC for your Survivalist abilities is 8 + your proficiency bonus + your Wisdom modifier.
At 3rd level when you choose this archetype, you may construct a deployable trap as part of a short or long rest. You may only have one trap ready to deploy at a time, as it requires patience and delicate care to make something so dangerous safe to transport. At the time you construct the trap, describe it to the DM and choose the effect or condition it imposes:
Blinded: Constitution saving throw, lasts 1 minute. If it fails, the victim gets a new saving throw at the end of its turn to end the blinded effect.
Poisoned: Constitution saving throw, lasts 1 minute. If it fails, the victim gets a new saving throw at the end of its turn to end the poisoned effect.
Pushed 10 feet and knocked prone: Strength or Dexterity saving throw (whichever is better). A prone target may stand again on its turn.
Restrained: Strength or Dexterity saving throw (whichever is better), lasts 1 minute. The victim gets a new saving throw at the end of its turn to end the restrained effect.
Stunned: Constitution saving throw, lasts until the end of the victim's next turn.
To deploy the trap, spend a bonus action while standing in or adjacent to the five-foot square you wish to trap. You may safely deploy a trap in an area occupied by an ally, but not by an enemy; an enemy in that space or within 5 feet can automatically disrupt your trap harmlessly. Once a trap is deployed, a character can detect it with a Wisdom (Perception) against your saving throw DC, and disarm it with a Dexterity (thieves' tools) check against your saving throw DC.
If a non-flying enemy enters or starts its turn in a space with an active trap, you can spend your reaction to activate the trap, forcing the target to make the saving throw appropriate to the effect. On a successful saving throw, the target avoids the effect; on a failed saving throw, it takes the listed effect for the duration specified.
When you deploy a trap, you may invest a spell slot into it. If you do so, detonating the trap also deals 2d10 damage for a first-level slot, plus 1d10 for every spell level higher than first. This damage may be lightning, thunder, or poison, as you choose. The damage is halved if the target succeeds its saving throw against the primary effect.
You can disarm and regain the use of any trap you deploy, as long as you have not activated it, by spending an action. You recover any spell slot invested in the trap. If not activated or disarmed, a deployed trap is active for a week.
EDITED: I've thought about this some more. I think the way to go here is to allow the Survivalist to gather up the parts of spent trap and reconstruct them with a minute of work. Short/long rests are for switching from one type of trap to another; you're really going to have a fresh trap ready to go in every fight, as long as you don't have to flee the scene or get teleported away or whatever. It winds up being about like recovering spent ammo. I think this might still be a little low on the power scale, in which case I'd give traps a baseline damage output of 2d6 piercing damage (scales to 4d6 at 11th level).
At 7th level, you can expand the area that your deployed traps affect. For each additional action or bonus action that you spend expanding a trap's area, you may add one 5-foot square to its area of effect, to a maximum of six 5-foot squares. The final area of effect must be contiguous. All trapped squares activate together - you cannot activate just one or two portions of the overall trap. When you invest a spell slot into an expanded snare, it deals 2d6 damage with a first-level spell slot, plus 1d6 for every spell level higher than first. To disarm an expanded snare, each five-foot square must be disarmed separately.
Further, you gain resistance against all damage dealt by traps or glyphs of warding.
At 11th level, when you deal damage to an creature twice in a single turn with any combination of weapon attacks or spells, you may shove that creature up to 10 feet as well. A creature that you shove in this way has disadvantage on saving throws against your traps until the end of its next turn.
At 15th level, you can prepare and safely store a second deployable trap each time you complete a short or long rest.
This is a pretty weird subclass, I am aware. It's really best for every kind of ranger except two-weapon-fighting rangers, since it's a bonus-action hog and only gets worse on that front as you go. I think there might be a real problem with limiting the deployable traps to once per short rest - there might be a lot of combats where you haven't had a short rest in awhile and you're cut down to baseline ranger abilities. I also wrote a list of trap-themed ranger and druid spells shortly after 5e launched, as an early attempt at a similar concept.
I set it up the way you see above to not go super-crazy overboard with traps; limiting them to one deploy in a single combat is the important part, so I guess I could change it to taking a minute or two to rig up a new deployable trap, but you can still only carry one at a time.
Staggering Strikes is an effort to help the ranger make traps go off with forced movement. Since it's 11th level, the archetype needs to provide a damage boost almost on par with an extra attack, so what I've done here is give you an occasional free use of something that is a kind of attack, if not damaging in itself, and gives you a chance at a big payoff from trap damage and conditions.
I deliberately didn't describe the trap mechanisms in great detail. My hope is that players demonstrate creativity in describing their mechanisms to the group, in a way that justifies damage types and conditions.
Resistance to trap and glyph damage was originally part of Second Snare at 15th level, but I moved it to Expanded Snares so that this niche ability would have eight more levels of gameplay to potentially see use.
In conclusion, I think this archetype presents an interesting playstyle in its current form, but it's under-powered - and that's a problem in the perpetually under-powered ranger. I just haven't yet had the idea that perfects the archetype.