There is a chance that Ultima is too slow against Prowess, but if control decks can construct themselves to routinely survive until turn five, Ultima blows them out
Creature - Shapeshifter Color tag templates(None) Jhoira's Familiar Flying Historic spells you cast cost less to cast
Its also, perhaps more importantly, a lot harder to counter when youve replicated it, as an opponent essentially needs a Whirlwind Denial or Flusterstorm, two counters that see minimal play at casual tables
That means you are not splashing that effect unless it is good enough for a real commitment to the color or lack thereof, just like how splashing Treetop Village is often not the best idea (but not always!)
We did see a mechanic that I feel is underappreciated: Disturb
It's great for going wide fun times