Twilight Ninja Nichirin, the Chunin

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.