So far in Time Spiral Block, the ability has been firmly blue. See Crookclaw Transmuter (its name a nod to the original P/T switcher, Transmutation) and now Planar Chaos's Merfolk Thaumaturgist (a color-shifted reference to Weatherlight's Dwarven Thaumaturgist).
Check out how, in the art, the merfolk has assembled a kind of underwater alchemical lab from Magically-strengthened bubble-vials. Around him float all kinds of spell ingredients while he warps some water before him.
Merfolk Thaumaturgist art by Steve Prescott
Note that Steve Prescott's design of the merfolk wizard was based on pre-apocalyptic Dominarian merfolk, as the card is time-shifted (and therefore represents a card from Dominaria's alternate past). See the Seventh Edition Merfolk of the Pearl Trident for the kind of merfolk reference Steve worked from.