Lets take a look at the cards and features that have currently been revealed for Universes Beyond: Assassins Creed
You miss out on one of the Marit Lage cards in a Svella, Ice Shaper deck, but Etali, Primal Conqueror is good enough, right
Szarekhs flying ability also makes him a hard-to-block commander, meaning you can rack up commander damage if needed
Should it die, the player gains four life, greatly fueling the "lifegain matters" theme of this school
If you dont want to look too hard for creatures that inherently have haste, this also isnt a problem, as you can simply give all of them haste with cards like Fervor, Concordant Crossroads, Rhythm of the Wild, or Fires of Yavimaya, making construction of a deck revolving around this card or Ogniss inclusion in a similarly aggressive deck quite manageable
Go on the attack with Atarka and engulf your opponents in dragonfire as your mighty army descends on the battlefield