My personal best Fire/Light Guild Conquest skillset.

Set skill priorities like so:
Phoenix Force - High
Rune of Ruin - Medium
Light Blessing - High
Meteor - High
Black Hole - High
Inferno - Low

Equip Ring of Perfect Subjugation. I find this ring and Ring of Critical Ferocity give me best results for bosses.

Enable the function "Don't use skills if there is a queued skill" in the settings. In this manner, you can leave your game on auto and still have a proper skill cast order.

Also, make sure you always set either Phoenix Force or Rune of Ruin on reserve depending on which has the current highest cooldown so all skills cast on break for the full damage effect. If pet skill is close in cooldown to Phoenix or Ruin, wait a few seconds more for the full pet buff on break as well.

Note: Your total damage will vary according to the legend effects you have on your runes.