Twilight Ninja Nichirin, the Chunin [BOSH-EN016] Common

Once per turn, during either player's turn: You can discard 1 "Ninja" monster, then activate 1 of these effects; This turn, "Ninja" monsters and "Ninjitsu Art" cards you control cannot be destroyed by battle or card effects. 1 "Ninja" monster you control gains 1000 ATK until the end of this turn.