During the side quest "That New Black Magic," players can prevent Giles from joining/appearing in battle with the Exemplar Commander.
This bug is somewhat significant since it makes the instance so much easier for players. Without Giles casting Weakness and Power Nova, players can more easily defeat the Exemplar Commander.
This bug acts similarly to the one that Medulla's battle once had, where players could fight Medulla one-on-one instead of Pork, Beans, and Sparck joining him in battle.
Hope this gets fixed soon!
- Anthony Skyheart Level 130
EDIT (November 18, 2018): I am aware that the Exemplar Commander is supposed to summon Giles as a minion after returning to the instance for the second time, but players can prevent this from happening by fleeing from the battle on the first turn before the Exemplar Commander summons Giles. Upon returning to the instance, the Exemplar Commander will not summon Giles.
A possible fix for this bug would be to make Giles spawn within the instance like any other mob rather than the Exemplar Commander summoning him on the first turn. Even if players stay after the first turn where the Exemplar Commander summons Giles, they're at a significant advantage since the summoning spell performed by the Exemplar Commander costs the majority of their starting pips.
Level 130