Does cursed mirror trigger ETB?

It has an ETB trigger that checks if it was cast, so Cursed Mirror will enter as Zacama, ETB, and look back to see that it was cast.

Does changing control trigger ETB?

If you use Act of Aggression to steal your opponent’s Hollowhenge Spirit, you don’t get to remove any other creature from combat, because control changes do not cause Hollowhenge Spirit’s or any permanents’ enters-the-battlefield abilities to trigger. This is because control-changing is not re-entering the battlefield.

Does Mirage Mirror have summoning sickness?

No, summoning sickness is not a copyable value The last are only considered if they have the wording “as [the object] enters the battlefield” or “as [the object] is turned face up”.

Does darksteel mutation remove counters?

However, Darksteel Mutation does not overwrite effects that change the enchanted creature’s power or toughness without setting it to a specific value (such as the ones created by Giant Growth or Glorious Anthem). It also won’t overwrite the effect of counters.

Does Cryptoplasm trigger ETB?

No. The cryptoplasm didn’t go away and come back. Its properties changed. If it had equipment etc on it, that would still be on it, if it had a temporary effect like ‘giant growth’ on it, that will continue to apply, and no creatures entered or left due to the cryptoplasm copying things.

When you gain control of a creature does it have summoning sickness?

Yes, a creature gets summoning sickness after taking control of it. 302.6.: A creature’s activated ability with the tap symbol or the untap symbol in its activation cost can’t be activated unless the creature has been under its controller’s control continuously since their most recent turn began.

When you take control of a creature does it enter the battlefield?

Taking control of your opponent’s creature will not trigger an “enters the battlefield” ability. A nontoken permanent “enters the battlefield” when it’s moved onto the battlefield from another zone.