Try intensifying the fire sensation. Not much else I can do here, unfortunately.
Ah, there you go - now the vine thing is acting quite oddly, whipping it's vines around itself rapidly. The stone parts are becoming more prominent, too.
Cut self out
run in a wide circle around it
throw spear at it.
Meet any vine attacks with a stab/dagger slice
Your persistence is admirable. You fail to get free this time, but the thing is writhing and thrashing much as yo uare, as if itself caught in a vegetative trap. Weirdest orgy ever.
Now that we have a solid link, either attempt to diffuse the magic that allows it to keep its body, but only if I can for sure pinpoint it.
If I can't, just freeze it (not literally) in place so my teammates can hack it to bits.
All the writhing and thrashing stops suddenly. Some of the rocks roll out of the vines and form a pile at the base of it. Others are too large to fall out, but they rest in the vine nets and so forth. Looks like yo got it this time.
Is the ridge taller than the guard? Or tall enough that if he were taken down, it wouldn't be obvious?
Jack continues his suggestion, the knife buffs Mordred's... dex, I guess. Or can the knife buff itself? If it can, it buffs its own will.
the ridge is taller than the guard. he is still in the clear, though, and not obscured from view of the top of the ridge, should another patrol come by. The knife cannot buff itself.
Jack gets the guy to walk into the woods. he is alert, and draws his weapon, but moves out a ways from the fort a short distance from Mordred. Mordred gets buffed, and a little twitchy. All set.