[Snake]

Kraken with Frostbite is already a little overused and the effect alone doesn't stack above the other, I very much prefer a fat Celsius to slow down the enemy's movement greatly, as Fern suggested above.

Galren could destroy tiles instead of getting bonus damage, on top of the knockdown.

Talvyd could spawn Air Shafts under the user and in all squares it hits, along with the increased range.

For Redgull, interference is the right wae to go, and of course all effects should be 4 rounds. It won't tip much the balance. There are actually tons of underwhelmed skills in the game that needs a check. This is certainly one of them.