The forgotten worldsoul

You can't spend mana to cast this spell.
this spell can be cast from graveyards or exile.
convoke, delve, menace, trample
when a delve ability is used, only creature cards
can be exiled. when a creature convokes a spell,
it's control sacrifices it.
{t} you may cast target creature card you own in
your graveyard or exile this turn. until end of
turn it gains "convoke, delve and you can't
spend mana to cast this spell."