Nashi, Moon Sage’s Scion looks very strong to me and I wouldn’t be surprised if it turns out to be the one of the absolute best cards in the entire set. Let’s break it down.

For three mana you get a 3/2 creature. That is not really up to today’s standards, but it’s triggered ability when you hit an opponent with it more than makes up for it. The important thing here is that it has more than one toughness, so it doesn’t die to Spikefield Hazard, which always feels like a freeroll when you get to kill a creature with what is supposed to be a land. 

When it connects, you get to exile both player’s top card until the end of turn and play one of them. And not even by paying mana for it, you actually get to cast it almost for free by using your life total instead! When I first read the card I thought you had to pay mana for it, which would still make it very good. But getting to pay life instead of mana makes it so much better. 

If you’re playing an aggro deck, your life total doesn’t really matter. You will enjoy increasing the pressure by casting a free card for a few life points and put your opponent into a deeper hole. Your only goal will be to make sure it connects every turn with a removal spell. There is plenty of good removal in black, but even something like Hagra Mauling’s stock just went up rapidly. In a Cube or EDH deck, there are some nice options like Shizo, Death’s Storehouse to make it connect even easier.

Even when they have a few blockers, you can usually get the first free hit in by using ninjutsu on an unblocked creature. The fact that you can get a hit with it out of nowhere makes it so much better as well because your opponent will never know when it’s safe to use their removal spell on other creatures. 

This can also be a great sideboard card against control in a deck with very few or ideally no creatures. In a control vs control mirror, you always board out all your removal spells for cards like Negate and Duress. Nashi would be the perfect card to bring in that situation because it is both cheap, so you won’t be giving up too much by tapping out for it early, but you also know what your life total won’t be getting pressured, so you should be able to play more than a few spells with it.

I feel like even just one hit can easily completely swing the game in your favor. Imagine playing a planeswalker with it for free on turn four. Or a Goldspan Dragon, or just anything that adds more pressure on your opponent by increasing your board presence. Thanks to the way it’s worded (“play” instead of “cast”), you can even play a land with its ability if you need to make a land drop!

This card will be great in Standard and Alchemy, but I can easily see it make it into formats like Historic in Mono-Black Aggro or even Modern, where a deck like Jund could be very interested in picking it up.