D&D 5E Vampiric Vines - Undead Plants

[Jimbro]

I'm making more undead because there's a CR gap (between 5 and 13) in the Monster Manual and I need a few more. My latest creation is the vampiric vine, because undead plants why not?

Take a look at it in the link below or in the attachment. Let me know what you think.
https://worldbuilderblog.me/2017/02/23/vampire-vines/

 

[aco175]

Overall it looks fine. The AC looks high for a plant-based creature. 18 makes it harder to hit for a CR12 creature, but should be more around 14-16. This may make it unmissable for a fighter. You could explain this by having vines passing through pieces of armor from past victims and thus making it harder to hit. Same thing with the escape DC20 from the grapple and the Con save 18 from the vampiric leech. The high numbers are good for one class and not for others.