Gladiator Naumachia (Common)

While you control a Gladiator Beast monster, all monsters your opponent controls must attack, if able. Once per turn: You can shuffle 1 Gladiator Beast monster from your hand or GY into the Main Deck, then target 1 Gladiator Beast monster you control; it gains ATK equal to its original DEF until the end of this turn (even if this card leaves the field). If this card in the Spell & Trap Zone is destroyed by card effect: You can activate this effect; this turn, Gladiator Beast monsters you control cannot be destroyed by battle.