Flavian - Colosseum of the Gladiator Beasts

Supreme Darkness

“You can discard 1 card; add 1 "Gladiator Beast" monster from your Deck to your hand. When an opponent's monster declares an attack: You can Special Summon 1 "Gladiator Beast" monster from your Deck, and it cannot be destroyed by battle. During the End Phase, if a "Gladiator Beast" monster was Special Summoned from your Deck this turn: You can Set 1 "Gladiator" Trap from your Deck. You can only use each effect of "Flavian - Colosseum of the Gladiator Beasts" once per turn.”