Usually an off-tank in trials, ideally a Warden with double ice staves. Main tank typically goes Dragonknight for Stagger and has to use Sword and Shield on at least one bar for Pierce Armor (Minor Breach).

A Warden healer can also do Brittle reasonably well, just they may lose some uptime while on the Restoration Staff bar (usually they don’t use double ice because they need Combat Prayer).

I say Warden because Winter’s Revenge and their status effect passive combine nicely to give the best uptimes. 3rd choice would be Warden Magicka DPS, but this is even less desirable with the new dual wield meta.