B.E.S. Crystal Core (CRV-EN021) [Cybernetic Revolution]

Put 3 counters on this card when you Normal Summon it. This card is not destroyed as a result of battle. If this card battles a monster, remove 1 counter from this card at the end of the Damage Step. If this card battles without a counter, destroy this card at the end of the Damage Step. Once per turn, during your Main Phase, you can change 1 face-up Attack Position monster on your opponent''s side of the field to face-up Defense Position.