B.E.F. Zelos (MZMU-EN114) [Maze of Muertos]

When this card is activated: You can add 1 "Boss Rush" from your Deck to your hand. All "B.E.S." monsters you control gain 500 ATK and DEF, your opponent cannot target them with card effects, and they cannot be destroyed by your opponent's card effects. Once per turn: You can Special Summon 1 "B.E.S." monster from your hand. If a "B.E.S." monster(s) is Normal or Special Summoned to your field: Place 1 counter on it.