24 Sept 2021
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."
24 Sept 2021
The creatures will enter the battlefield simultaneously. They will see each other enter for the purposes of triggered abilities.
24 Sept 2021
Once a creature with decayed attacks, it will be sacrificed at end of combat, even if it no longer has decayed at that time.
24 Sept 2021
Decayed does not grant haste. Creatures with decayed that enter the battlefield during your turn may not attack until your next turn.
24 Sept 2021
Decayed does not create any attacking requirements. You may choose not to attack with a creature that has decayed.
24 Sept 2021
If any creature cards put onto the battlefield this way become permanents that aren't creatures because of another effect, those permanents won't be Zombies, but they will gain decayed.