Honest (BLMM-EN006) [Battles of Legend: Monster Mayhem]

During your Main Phase: You can return this face-up card from the field to the hand. During the Damage Step, when a LIGHT monster you control battles (Quick Effect): You can send this card from your hand to the GY; that monster gains ATK equal to the ATK of the opponent's monster it is battling, until the end of this turn.