Chained Devourer

Shroud
At the beginning of your upkeep, if Chained Devourer has 16 or more +1/+1 counters on
it, it loses all abilities then gains trample and must attack each turn if able.
Sacrifice a creature: Put X +1/+1 counters on Chained Devourer where X is the sacrificed creature's toughness.
"It won't stay chained up forever"