My Undead Horde Awakens is a common Ongoing Scheme card from Archenemy Schemes (OARC), collector number 29★. Current market price: $16.69, TCGplayer market prices via Scryfall.
(An ongoing scheme remains face up until it's abandoned.) At the beginning of your end step, you may put target creature card from an opponent's graveyard onto the battlefield under your control. When a creature put onto the battlefield with this scheme dies, abandon this scheme.