To be honest, there are so many possibilities with Mairsil that Im not even sure where youd start
(2022-04-29) Casualty N means As an additional cost to cast this spell, you may sacrifice a creature with power N or greater. and When you cast this spell, if a casualty cost was paid for it, copy it
"If a toon monster WOULD BE destroyed: you can banish this card from the GY instead."
They may not be able to kill things they tussle with, but if they could already block your stuff and survive that will still be true
Chart shows the price of Premium Card Collection [Best Selection Vol.4] at the end of each month going back as long as we have tracked the item.
Perhaps, by chance, there are tons of players running this that aren't using EDHREC - I suppose taking the time to submit a deck to an online database is not very Timmy, so there could be something to that