Rotten Reunion
Instant
Exile up to one target card from a graveyard. Create a 2/2 black Zombie creature token with decayed. (It can't block. When it attacks, sacrifice it at end of combat.)
Flashback 
(You may cast this card from your graveyard for its flashback cost. Then exile it.)
Aunt and Uncle Greyfield loved dinner guests.
Illustrated by
Innistrad: Double Feature#119CommonEnglishLegality
Rulings
Decayed represents a static ability and a triggered ability. “Decayed” means “This creature can’t block” and “When this creature attacks, sacrifice it at end of combat.”
Decayed does not create any attacking requirements. You may choose not to attack with a creature that has decayed.
Decayed does not grant haste. Creatures with decayed that enter the battlefield during your turn may not attack until your next turn.
Once a creature with decayed attacks, it will be sacrificed at end of combat, even if it no longer has decayed at that time.