Promise of Tomorrow is a rare Enchantment card from Commander Legends (CMR), collector number 39. Current market price: $0.35 (foil $0.38), TCGplayer market prices via Scryfall.
Whenever a creature you control dies, exile it. At the beginning of each end step, if you control no creatures, sacrifice this enchantment and return all cards exiled with it to the battlefield under your control.