Bright Throats Jewelry Triune with 1 reduced spell cost, 1 magicka regen, and 1 Spell Damage enchants, shacklebreaker
Infused Frost Staff w/ Weapon damage enchant, shackle breaker Decisive Resto Staff With magicka/stamina poisons Bright Throats Impen Sash, Bright Throats Impen Gloves, Shacklebreaker Heavy Impen Sabatons, Shacklebreaker Heavy Infused Greaves and Cuirass. Thurvoken Impen Pauldrons and Helm. All Prismatic Defense Glyphs on armor.

Witch Mother's Brew drink
Immovabilty, Health, and Magicka potions
Immovabilty, Magicka, Detect potions

Buff with Bull Netch, Ice Fortress, and Enchanted growth every 20 seconds.

Primary responsibility
You are main source of defile in the group because you have AOE defile skill.
Defile and CC with Corrupting Pollen and and Time Freeze.
When Crown calls for ulti dump cast; corrupting pollen, time freeze, Prox Det, permafrost, Deep Fissure, Elemental blockade, corrupting pollen, time freeze.
Keep multiple meatbag catapults in inventory, if you are on seige it should be a meatbag, during assaults on contested keeps You should be meatbaging counter

Secondary
Shimmering shield is great for ultimate generation
Deceptive Predator is mainly there for passives, but also a source of major expedition and stamina recovery.