B.E.S. Crystal Core 021

Card text

When this card is Normal Summoned, put 3 counters on it. This card cannot be destroyed by battle. If this card attacks or is attacked, remove 1 counter from this card at the end of the Damage Step. If you cannot, destroy it. Once per turn, during your Main Phase, you can change 1 face-up Attack Position monster your opponent controls to face-up Defense Position.