First idea is a rework for the T4 fire card Virtuoso. Make it's trumpet attack the basic attack. Reduce a bit it's damage, and can only knock back large and smaller units. Give it a new ability on cooldown that increases damage dealt by ally units by 25% for 20seconds with a 20energy cost.
And here's my crappy idea at making a T1 swift unit for frost. (Art and unit would be smaller core dredge in a squad of 4)
Grinding teeth: while attacking near an ally building, the Dredge Tendril will do a small aoe damaging shockwave dealing 8dmg per second to nearby enemies.
Earth Dive: While moving around unit takes 25% less damage and is unaffected by unit collision slowing effects.
Swift: Well we all know what it does.
Recore: Cost 60 energy: Combine 4 dredge tendril squads while having atleast two frost orbs to turn into a Core dredge with 75% life but unable to move for the next 20seconds.