Crowded Crypt

{T}: Add {B}.
Whenever a creature you control dies, put a corpse counter on this artifact.
{4}{B}{B}, {T}, Sacrifice this artifact: Create a 2/2 black Zombie creature token with decayed for each corpse counter on this artifact. (A creature with decayed can't block. When it attacks, sacrifice it at end of combat.)

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Aetherdrift Commander

Midnight Hunt Commander

{T}: Add {B}.
Whenever a creature you control dies, put a corpse counter on Crowded Crypt.
{4}{B}{B}, {T}, Sacrifice Crowded Crypt: Create a 2/2 black Zombie creature token with decayed for each corpse counter on Crowded Crypt. (A creature with decayed can't block. When it attacks, sacrifice it at end of combat.)

{T}: Add {B}.
Whenever a creature you control dies, put a corpse counter on Crowded Crypt.
{4}{B}{B}, {T}, Sacrifice Crowded Crypt: Create a 2/2 black Zombie creature token with decayed for each corpse counter on Crowded Crypt.

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.

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.”

Once a creature with decayed attacks, it will be sacrificed at end of combat, even if it no longer has decayed at that time.

Zombie

Decayed (This creature can't block. When it attacks, sacrifice it at end of combat.)