Khulai Worm

Devour 2 (As this enters the battlefield, you may sacrifice any number of creatures. This creature enters
the battlefield with twice that many +1/+1 counters
on it.)
Remove two +1/+1 counter : Regenerate
Each time a creature die after being dealt combat damage by Khulai Worm, add X +1/+1 counters
on Khulai Worm were X is equal to that creature toughness.