Number 24 [Dawn of Heroes]

When Number 24 enters the field or at the beginning of your Main Phase 1 during each of your turns, place 1 Barrier Counter on Number 24.
If a Barrier Counter is placed on Number 24, Number 24 gains "If Number 24 is dealt damage, remove 1 Barrier Counter from Number 24 and the damage becomes 0 instead."

At the end of each of your turns, if 3 or more Barrier Counters are placed on Number 24, dull Number 24.