The big one here is Dimir Midrange
If we can get down an Ensnaring Bridge or sweep the board with Anger of the Gods, it often buys us a few turns, which is usually enough to ultimate one of our Chandras to win the game
The Raven Man This fun on-curve 2/1 drop can tap for four at sorcery speed to make everyone else discard
Carnage Tyrant, Ghalta, Primal Hunger, and Forebears Blade are multiplayer stars, but the clutch card here is Conclave Guildmage, which can tap to give the team trample or to make a token
It also does provide closing speed like I discuss in this article, so I think it is worth experimenting with
Then I tried a variety of sideboard cards with some being dead awful (looking at you Wasteland and Dust Bowl) and some being kinda ok, like 4 Living Death and Null Rod