#copy effects

Related question, if I have a Stifle, can I counter the ability to make the token after they have sacrificed both their lands?

Thank you!

For those who don't know the combo, I'll explain it step by step:

The first step is to activate Thespian's Stage to copy Dark Depths. When this ability resolves, Thespian's Stage becomes a copy of Dark Depths, but one without any ice counters on it (since it didn't enter the battlefield as a copy of Dark Depths).

Before any triggers go on the stack, the game checks state-based actions and sees that a player controls two legendary permanents with the same name. To rectify this, they put one of them into their graveyard. (In order for the combo to work, the original Dark Depths must be the card sent to the graveyard here.)

Now we put the Stage/Depths's "no ice counters" trigger on the stack. This is a relatively normal trigger and can be responded to with abilities like Strip Mine to destroy the land. Countering the trigger with Stifle won't do anything productive, however, since the state trigger for no ice counters will just trigger again once the first iteration of the trigger leaves the stack.

When the trigger goes to resolve, the Stage/Depths will be sacrificed (if it's on the battlefield still). If it was sacrificed this way, then the Marit Lage token will be created. This is all a single trigger with no opportunity to respond to anything between the sacrifice of the land and the creation of the token. (If the ability was worded "When you do, ..." rather than "If you do, ...", it would create a new trigger for the rest of the effect, but Dark Depths well pre-dates that templating technology.)

The net result here is that both lands are in the graveyard and a Marit Lage token has been created. The interaction points during the process are limited due to Dark Depth's ability being both able to re-trigger if countered and being only a single trigger, leaving no way to stop it once both lands are in the graveyard.

That interaction is working as intended.

While it’s true that effects that add and remove abilities apply in timestamp order, mutate doesn’t work by giving abilities and the like, but rather by changing the copiable characteristics of the mutated creature. Since mutate is a copy effect, it applies earlier than Frogify’s effect and so any ability that would be gained by the creature is stripped away by Frogify before it can be relevant.

Just a copy of creature B. The effects of Mutate apply in the same layer as normal copy effects, so whichever effect is newer will win out. Making a mutated creature into a copy of something else will just make it a copy of that thing without its mutations. In the case of Volrath, he’ll go back to normal in the cleanup step (complete with mutations).

No, it won’t.

Spark Double will enter the battlefield as a Paradise Druid in every way, including its name. Since it has the same name as another creature you control, Guardian Project’s secondary condition won’t be satisfied and it won’t trigger.

Lazav, the Multifarious has a new template for these sorts of effects. Previously, the copy effect would ignore the characteristics that are excepted this way, but now they just overwrite those values with the listed value.

What this means for Necrotic Ooze et al. is that instead of keeping their original name as they would before, they now become named Lazav, the Multifarious (or whatever other name is tied to the ability). This is, of course, a problem if you already control a Lazav.

It'll just be a copy of Essence of the Wild.

Yes, you still have to exile the tokens that were created by Saheeli’s ability.

The delayed trigger only cares that those permanents were created by Saheeli’s ability, not what they happen to be at the moment of the trigger resolving. There’s no way to save them with Brudiclad’s illusions.