"It's got me! HELP!"

[fba827]

Sacrifical Limb: (Standard, At Will) Lose 10 HP. The head gains 10 HP.

Do your PCs have any/many powers that vary depending on bloodied status of the enemy (tiefling racial power, or some class powers)? If so, your Sacrificial Limb power may become troublesome to track if it takes it causes the head to go up and down from bloodied status often.
If they don't, it's not a big deal... If they do, then you may want to consider it "The head gains 10 temp hp" -- it has the same effect but it won't stack with other applications and it avoids the possibility of going up/down/up/down on bloodied status.

Death Throes (Immediate Reaction, when the Head reaches 0 HP, Encounter). Make a basic attack against the nearest enemy, then retreat.

Since your basic attack is already defined, just simply it for yourself and replace "basic attack" with the word "slam"

 

[chronoplasm]

For the tentacles, simply take the Roper's powers and attach them to some generic brutes or minions.

 

[Rechan]

I ran the session wiht the above stats I used.

I only had at most 3 tentacles on the field at once. Which probably limited things a little. Namely, they died rather fast. Leaving the bulette behind, and the bulette couldn't really put a huge dent into one person enough to make it truly threatening.

However, the walls and pits and such appearing at the end of every round was very fun.