1h Weapon of transmutation sharpened with absorb magicka enchants, double damage poisons, shield of transmutation impen with Max Magicka enchant, transmutation Inferno staff infused with weapon damage enchant, transmutation jewelry Triune with 1 Spell Damage, 1 reduced spell cost, 1 magicka regen enchants, Earthgore monster set impen, 5 Kragnac’s Armor pieces in impen, Tristat enchants on all armor.

Witch Mothers Brew
Unstoppable, Magicka, Health potions

Primary responsibility
You are number one fast rezzer if anyone drops you should be rezzing if you need soul stones let the group know and they will gladly donate you some, you shouldn’t ever need to buy any.
Next most importantly is to drop ultimates when crown calls for ulti dump, if it is at a choke point or objective drop Solar prison, if it is mobile or open area drop eye of storm.
Your primary rotation is going to be Prox Det, Explosive Charge, Elemental Blockade, swap bar, Ritual of Retribution, Restoring Focus, Solar Barrage, Radiant Aura, Purge, mystic orb. Repeat.
Whenever your are stationary i.e. sieging or standing on an uncontested flag you should have Ritual of Retribution and Restoring Focus down and if hit with something start with a purge.

Tertiary
Mystic Orb is a great skill, but only when backing up or running. The orb moves slower than you do so typically it will always be behind you. It has a fairly high cost so don’t just spam cast it, cast one do a couple of light attacks, cast another it’s something to cast with light or heavy attacks from range while holding ground, or backing up.

Key points of build
Elemental blockade can proc back bar enchants while on front bar.
Ritual of retribution is the groups main source of transmutation so try for maximum uptime.
Radiant Aura is one of the best sources of minor magicka steal in the game. But a complete waste of a cast if there are no enemies near to hit.