After we 3-manned Toth & Zorn we had a few tries on Firebrand & Stormcaller but the damage of both their cleaves hitting everyone proved too much to heal. We are still trying to devise a strategy for that fight. Anyway we got a 4th (tank) and also killed those.
Also... why is it that Sentinels can't queue as tanks on LFG? :P
[UPDATE] Firebrand and Stormcaller 3 manned