Momir: Should you play 9-drops?

9-drops are sometimes worth making in Momir Basic.

Using the Gatherer lists of all the 8-drops or bigger you could make, plus my own arbitrary evaluations in this doc, 9-drops are a bit more likely than 8-drops to steal games, but they're also a bit more likely to do nothing.

In most Momir scenarios, if you get to 9 mana somehow, you'll want a big flyer (or a big haste creature or such) to drop on the board and attack / block with -- that means you should make an 8. A lot of 9's have disappointingly low power and toughness.

If the board is stalled out or it looks like the game will go long for some reason, 9's have about the same average value as 8's, since now you can grind incremental advantage from the blue, red, or green Bringer.

Bernhard Zander points out that Denizen of the Deep and Akron Legionnaire are 8's which almost automatically lose you the game. He thinks that this makes 9's slightly better overall, and he calculates the chance of hitting a suicide creature at 1% or 2%. A good rule would be to play 9's if you're winning and 8's if you're losing or if the game is close. (If you are certain to win, he recommends just making a 6.)

(Of course, you should never miss making a drop just to get to 9 mana -- the optimal plan is still maxing out at 8 by starting on turn 2 or 3. The choice of 9-or-8 should only come up after you get a random creature that generates extra mana.)

It also turns out you shouldn't play 10-drops in Momir Basic:

By my count, of the 14 possible creatures you could get for ten mana, only 3 are awesome (Jin-Gitaxias, Kozilek, and Progenitus) while most are either ineffective or have big upkeep costs. Better to just make an 8 or 9 and leave up some mana.

The 11- and 12-drops are pretty good though:

None of the 11's or 12's has haste or an enters-the-battlefield bonus, so you can activate Momir for 11 or 12 after combat without losing value.

There are no 13s or 14s. If you pay 13 or 14 to a Momir avatar, you will get nothing. If you pay 15, you'll get either an Emrakul or a 9/14 trample creature. There's no reason to pay more than 15.