Oh my god is Nahiri powerful in Mardu. From assembling combos, to exiling stuff, to looting into our outs, she's got it all. Easy 3-of. Many people dislike her because if we don't have control of the board or near control of the board, she's underwhelming. Note that
Liliana of the Veil
is even worse if we don't have partial or total control of the board since your opponent gets choice for her -2 and if they have a boardstate, this isn't the time to be attacking their hand. However, no one questions that Lili is fantastic. This is because in this deck, we usually have partial or total control of the board. Very few, if any, decks in modern can make the game state such that Nahiri is bad. Especially when we're packing removal for days and grindy cards like
Lingering Souls
.
Speaking of which, the value of cycling away a
Lingering Souls
with Nahiri can not be understated. It's half of a card of advantage, since you only get half of a Lingering Souls, but in many matchups, even half of a spirit team will do more than trade 1-for-1/2 with your opponent.
The draw fixing from Nahiri's +2 is very nice. It's not the primary reason I play the card, but it's a factor to keep in mind for sure. In a topdeck war, being able to play 24 lands to get enough early, then be able to dig for gas in the late game is very relevant.
So why no Emrakul? Because it's win-more. This deck is strong because it's perfectly capable of winning the game without ever seeing Nahiri on the back of cards like Obzedat. And, in matchups like Tron, Nahiri is, somewhat surprisingly, actively bad. In my testing so far, if I've gotten off Nahiri's ult, I've won with Obzedat, Kalitas, or Blood Baron and not needed Emrakul. However, if I happen to draw Emrakul or I don't draw Nahiri, the game gets much harder since Emrakul is extremely dead in my hand, which is not the kind of card you want to be playing when you're deck is at its best in a topdeck war, and without Nahiri ul, an Emrakul deck will struggle significantly to win.