I am working on a Mairsil, the Pretender deck and kinda looking around at what others have done as well. One card that pops up alot is Shifty Doppelganger, a very interesting card i was unaware of.
I do have a quick question of how it interacts with Mairsil's ability. My fear is i stick something in play someone kills it and my Mairsil gets stuck in limbo.
If i put a creature in play and exile Mairsil, can i change him to the command zone, and then when EOT comes around and i sac the creature will it be able to get him from command zone? I know the "fixed" o-ring abilities you can because they do not specify where the card is moving from, so is this similar?
This works, assuming you're playing the Commander variant, which has C.R. 903.9, and Mairsil is your commander. An ability like Shifty Doppelganger's tracks the permanent that was exiled in the first zone it goes to, even if that zone isn't exile, as long as the permanent was moved to a public zone, such as the command zone (C.R. 400.7h, 400.2), and that card didn't leave that zone (C.R. 400.7). See also this thread.
EDIT (Aug. 29): Note also that even if the permanent exiled this way isn't moved to exile, that part of the cost is still considered paid (C.R. 117.11; see also this thread).
Keep in mind that if the creature Mairsil brings up with the Doppelganger dies before the end step, he's not coming back with this ability for the creature has to be sacrificed for Mairsil to return.
Of course, in commander you can just cast him again from commandzone.
The rules for the Commander variant changed with Core Set 2021 in a way that materially affects this answer.
The answer to comment 1 is now: No, this won't work, even if you're playing the Commander variant, which has C.R. 903.9, and Mairsil is your commander.
Now, if Mairsil is your commander and you exile Mairsil with the ability it gains from Shifty Doppelganger, a state-based action will then give you the option to move Mairsil from exile to the command zone (C.R. 903.9a). If Mairsil moves to the command zone this way, however, the ability won't bring Mairsil back to the battlefield, since it has left exile (C.R. 400.7, especially C.R. 400.7h). Mairsil will return this way only if it hasn't left exile in the meantime.
I do have a quick question of how it interacts with Mairsil's ability. My fear is i stick something in play someone kills it and my Mairsil gets stuck in limbo.
If i put a creature in play and exile Mairsil, can i change him to the command zone, and then when EOT comes around and i sac the creature will it be able to get him from command zone? I know the "fixed" o-ring abilities you can because they do not specify where the card is moving from, so is this similar?
Thanks for the help everyone!
This works, assuming you're playing the Commander variant, which has C.R. 903.9, and Mairsil is your commander. An ability like Shifty Doppelganger's tracks the permanent that was exiled in the first zone it goes to, even if that zone isn't exile, as long as the permanent was moved to a public zone, such as the command zone (C.R. 400.7h, 400.2), and that card didn't leave that zone (C.R. 400.7). See also this thread.
EDIT (Aug. 29): Note also that even if the permanent exiled this way isn't moved to exile, that part of the cost is still considered paid (C.R. 117.11; see also this thread).
EDIT (Jul. 2, 2020): See comment 5.
Of course, in commander you can just cast him again from commandzone.
The answer to comment 1 is now: No, this won't work, even if you're playing the Commander variant, which has C.R. 903.9, and Mairsil is your commander.
Now, if Mairsil is your commander and you exile Mairsil with the ability it gains from Shifty Doppelganger, a state-based action will then give you the option to move Mairsil from exile to the command zone (C.R. 903.9a). If Mairsil moves to the command zone this way, however, the ability won't bring Mairsil back to the battlefield, since it has left exile (C.R. 400.7, especially C.R. 400.7h). Mairsil will return this way only if it hasn't left exile in the meantime.