Tainted Adversary
Creature — Zombie
[[ keyword: "Deathtouch" ]]
When this creature enters, you may pay 
any number of times. When you pay this cost one or more times, put that many +1/+1 counters on this creature, then create twice that many 2/2 black Zombie creature tokens with decayed.
Tuan Duong Chu
Rulings
After you pay the {2}{B} cost one or more times, a second ability triggers. Players may respond to the new ability at that point. As that ability resolves, Tainted Adversary gets its counters and the tokens are created.
(wotc • 2021-09-24)
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."
(wotc • 2021-09-24)
Once a creature with decayed attacks, it will be sacrificed at end of combat, even if it no longer has decayed at that time.
(wotc • 2021-09-24)
Decayed does not create any attacking requirements. You may choose not to attack with a creature that has decayed.
(wotc • 2021-09-24)
Decayed does not grant haste. Creatures with decayed that enter the battlefield during your turn may not attack until your next turn.
(wotc • 2021-09-24)
Printings
Rulings
After you pay the {2}{B} cost one or more times, a second ability triggers. Players may respond to the new ability at that point. As that ability resolves, Tainted Adversary gets its counters and the tokens are created.
(wotc • 2021-09-24)
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."
(wotc • 2021-09-24)
Once a creature with decayed attacks, it will be sacrificed at end of combat, even if it no longer has decayed at that time.
(wotc • 2021-09-24)
Decayed does not create any attacking requirements. You may choose not to attack with a creature that has decayed.
(wotc • 2021-09-24)
Decayed does not grant haste. Creatures with decayed that enter the battlefield during your turn may not attack until your next turn.
(wotc • 2021-09-24)