U.A. Stadium (AP08-EN024) - Astral Pack 8 Unlimited

If a "U.A." monster is Normal Summoned to your side of the field: You can add 1 "U.A." monster from your Deck to your hand. Once per turn, if a "U.A." monster(s) is Special Summoned to your side of the field: All monsters you currently control gain 500 ATK (even if this card leaves the field).