Constellar Praesepe (HA07-EN061) - Hidden Arsenal 7: Knight of Stars Unlimited

2 Level 4 "Constellar" monsters // Once per turn, during the Damage Step of either player's turn, when a "Constellar" monster you control is attacking or being attacked: You can detach 1 Xyz Material from this card; that monster gains 1000 ATK, until the End Phase.