Rotting Leviathan

Trample, Gargantuan (This Creature cannot be
blocked except by a Creature with Greater Power.)

When this Creature enters the Battlefield, place 4
+1/+1 counters on it. Each time it makes an attack,
remove a +1/+1 counter from it and place it on
another Creature you control. When this Creature
has no +1/+1 counters remaining, it gains Decayed.

Regenerate - {u}{t}: Place one +1/+1 Counter on this Creature.