When you enter the arena, there is a hard Agony Resistance check, resulting in being instantly downed if you do not have the minimum requirement.

Mai Trin is protected by ten stacks of Captain’s Shield, each stack reducing her incoming damage by 10%. The only way to remove stacks is by pulling her into electric fields from Horrik's Electric Blast. Standing in the electric field will remove one stack per second from her.You can easily recognize it from the icon above the targeted player and the telegraphed purple electric fields on the ground. Horrik's other projectile attack, Cannon Blast which deals damage and inflicts Burning on targets can be reflected and absorbed.

The key is to stack on Mai Trin during the whole fight: this way she will always be in an electric field, even if she teleports to the furthest player away.

Every 25% health, Mai Trin disappears and additional enemies spawn while fiery cannons shoot. Change your target to Horrik and bring him down by 25% of his health to bring Mai Trin back. Use Pull abilities to stack the adds together and cleave them down.

Keep in mind that with each phase, more cannons start shooting at you. The fight can get quite chaotic in the last phases. Luckily, Mai Trin won't have any protective stacks below 25%, so focus your damage on her. It is vital to bring reflections and Stability to counter the elite adds that spawn after Mai Trin disappears at 25%. Killing Mai Trin finishes the fractal, therefore there is no incentive to kill Horrik before that unless you are going for the Horrik's Horror achievement (see below) .