Thankfully that extra turn ability is difficult to chain
Looking at the two of them I feel that it is obviously time to break some eggs
Between the card's two abilities, Meren synergizes in incredible fashion with sacrifice outlets and Aristocrats synergies that can provide experience counters as well as self-milling effects that can provide a Meren player with additional options of which cards they'd like to return to play.
Honorable Mention: Yuriko, the Tigers Shadow While neither a rat nor directly synergistic with rats, Yuriko, the Tiger's Shadow does have commander ninjutsu, and theyre both one of the best Dimir commanders, and one of the best aggro commanders
When you can play it however it is Thundermaw plus, all that efficient evasive aggression combined with removal protection
Wizards of the Coast gets to pull out the stops and showcase a whole bunch of different methods Surveil can be used