Does Meren's ability count as 'casting' for cards like Ulamog, the Ceaseless Hunger?
Putting a creature directly onto the battlefield isn’t the same as casting it.

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Does Meren's ability count as 'casting' for cards like Ulamog, the Ceaseless Hunger?
Putting a creature directly onto the battlefield isn’t the same as casting it.
Hey! Question about Shirei, Shizo's Caretaker: Will his ability return creatures that died before he was played, but on the same turn? -Thanks!
No.
Shirei has to be on the battlefield both when the creature dies and when the end step begins in order to be able to return it to the battlefield.
When you use Lin Sivvi's activated ability, can you search for a (rebel) sorcery/instant? (eg Crib Swap)? The text, 'put that card into play' is a little vague as to whether it's referring to permanents, or it makes it morph or you can play the spell. Thanks!
You can’t search for an instant or sorcery since it’s not a permanent card, but you can find an aura like Bound in Silence.
If I rally the ancestors and return cliffhaven vampire, kalastria healer and an expedition envoy, will kalastria healer trigger thrice for one damage and one life gain each, triggering cliffhaven vampire thrice or just once for three life gain and three damage, triggering cliffhaven vampire once? - Thanks
When all three enter the battlefield, Kalastria Healer will trigger three times. When the first trigger resolves, Cliffhaven Vampire will trigger and then resolve.Each Kalastria Healer trigger that resolves will trigger Cliffhaven Vampire again.At the end of the whole process, you’ll have gained 3 life and each opponent will have lost 6 life.