During either player's turn: You can discard this card; until the End Phase, "Gravekeeper's" monsters you control cannot be destroyed by battle.
Rulings
Individual Card FAQs
You can activate the effect of "Charm of Shabti" during the Damage Step.
"Charm of Shabti" is like a reverse-"Kuriboh": you take damage from the attack as normal, but your monster is unharmed.
Netrep Rulings
โCharm of Shabtiโ can be discarded from the hand in response to a face-down Gravekeeper monster being flipped up by an attack if that Gravekeeper monster would be destroyed by an attack.