Agyrem is a common Plane — Ravnica card from Planechase Anthology Planes (OPCA), collector number 11. Current market price: $4.97, TCGplayer market prices via Scryfall.
Whenever a white creature dies, return it to the battlefield under its owner's control at the beginning of the next end step. Whenever a nonwhite creature dies, return it to its owner's hand at the beginning of the next end step. Whenever chaos ensues, creatures can't attack you until a player planeswalks.