
Charlatan |

Hullo friends, Q about the A Vine.
It's reaction reads like an ambush mechanic, but it only costs a reaction, so is it supposed to use it every turn? If that was the case, why didn't the reaction create an "aura of plant grabbiness" that stayed with the vine?
I ran a fight the other day, which was very fun, but as I running it I realised it wasn't and one-and-done ability. So each new turn, assuming it moved, it could call new plants to stir and possibly entangle it's foes. I didn't use it as I thought the fight was enough as was (and vines are great fun to whip PCs with) but I think I ran it suboptimally.
Nothing wrong with that, but is the intent a constant 20-ft "hopefully you're tangled" fight? It feels like an aura of animation, but it isn't.
Thanks in advance.
Grasping Foliage --Reaction-- (primal, transmutation)
Trigger The assassin vine detects a creature within 20 feet via tremorsense
Effect The assassin vine causes vegetation within a 20-foot emanation to writhe for 1 round, turning this area into difficult terrain. When a creature starts its turn in this area, it must attempt a DC 20 Reflex save. On a failure, it takes a –10-foot circumstance penalty to its Speeds until it leaves the area, and on a critical failure it is also immobilized for 1 round. A creature can attempt to Escape to remove these effects. Assassin vines are immune to Grasping Foliage.

Franz Lunzer |

Well, it is a reaction, with the trigger being "detects a creature within 20 feet via tremorsense".
... It is an imprecise sense with a limited range (listed in the ability). Tremorsense functions only if the monster is on the same surface as the subject, and only if the subject is moving along (or burrowing through) the surface.
Characters not moving (leaving the square) should suffice to not trigger the reaction.
If you think that is too easy of a solution, you could apply a Special Circumstances-Penalty to the characters checks, to account for unusual body movement while the characters make sure to not move their feet while swinging at the vine.