原文Because creatures controlled by opponents aren't dying due to Gisa's replacement effect, any "when [this creature] dies" triggered abilities those creatures have won't trigger.
原文Gisa does not grant haste to the creatures that are returned to the battlefield, so you normally won't be able to attack with them the turn they are returned.
原文If a creature your opponent controls would die and more than one effect would cause it to be exiled, that opponent chooses which one to apply. If the creature is exiled due to some other replacement effect, it will not be returned to the battlefield with Gisa.
原文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."