Isaac, Horde Forger

You can only cast creatures spells from graveyards. You may spend mana as though it were mana of any color to cast creatures spells from a graveyard. A creature cast this way becomes a
night creature in addition to its other types.
If a creature cast this way would die, exile it instead.
At the beginning of your end step, sacrifice a night creature. If you can't, sacrifice Isaac, Horde Forger.