The healer’s job sounds very easy: keep everyone alive as much as possible. Keep an eye on the HP of other players and heal accordingly. Of course you should still do some damage to the Vale Guardian if possible, but it’s not your main priority.
During the split phases, the healer goes to the Blue Guardian.
The Auramancer uses full Berserker gear.
Ideally all the armor pieces have Superior Runes of the Scholar.
Ideally these weapons have Sigils of Force and Sigils of Air.
The stats that should be included in your food and utilities are: