Building an undead Treant - Suggestions?

[QuaziquestGM]

Don't worry about the tree so much as the extras.

Suddenly being jumped by the racoon goul while fighting the undead tree is something a player will remember forever.

Skeletal cats, arcorn thorwing zombie chipmunks....tiny squirrel wraithes, swarm of living hornets, hell...flock of reanimated kites (charlie brown) with entagleing strings.

And the undeath throws....having the thing dissolve into sawdust an a swarm of necromatic termites....

 

[Quartz]

How about this for an unusual variant on an undead lich treant: when the treant is destroyed the PCs have to destroy the undead seeds as well lest the lich arise as new.

Bonus points if the seeds are being scattered here and there by undead minions.