Sabatiel - The Philosopher's Stone (DLCS-EN017) [Dragons of Legend: The Complete Series]

If you have a "Winged Kuriboh" monster in your GY: Pay half your LP; add 1 "Polymerization" Spell or "Fusion" Spell from your Deck to your hand. If this card is in your GY: You can banish 3 copies of "Sabatiel - The Philosopher's Stone" from your GY, then target 1 monster on the field; it gains ATK equal to the ATK of the monster on the field with the highest ATK (your choice, if tied), until the end of this turn.