Completing the quest Divine Might will simultaneously complete this mission, and it has additional rewards.
After arriving in Ru'Aun Gardens take the center portal to the main island. Travel straight to the center of the island.
Be careful not to stray from the middle path, for the Groundskeepers along the walls on the blue pads are aggressive to magic, as per usual, but in addition, all Groundskeepers in the area that are standing still near a blue pad are aggressive via sight as well.
In the Shrine of Ru'Avitau, continue straight until you find an unmarked target on the wall. Examine it to receive a cutscene.
If you intend to do Divine Might click the point again once the first cutscene completes to flag Divine Might so you can get your Ark Pentasphere. See the Divine Might page for information about the mini quest.
If you do not get this cutscene, you can still do the fight, but you will not be credited for it for this mission.
You must defeat all the Ark Angels for the mission, be it one at a time via this mission, or all at once via Divine Might. The Battlefields for them are in La'Loff Amphitheater on the islands surrounding Ru'Aun Gardens, accessible by the Red Portals.
Reaching the Battlefields
When you visit each island for the first time, make sure you register all 5 Home Points for Ru'Aun Gardens. These home points can be used to warp you to the entrance of each section of La'Loff Amphitheater.
To reach the different islands, activate the pincer stones and take the Blue Portals. Where you will then take the red portals to reach the battlefield islands and homepoints.
Warps around the circular area of the Battlefield, except during Blood Weapon, when it will follow the current target. Does not follow up the stairs (except during Blood Weapon, most likely).
Tips & Tricks - Mages stand at the stairs and attack/heal from there as the AoE attack can be deadly. Damage dealers simply melee. Shadow Images are very useful to evade most spells as AoE ones are not used that often.
Unique weapon skill Havoc Spiral: (AoE 100-300 damage plus Sleep and Weight, absorbed by Shadow Images).
Has some attack which causes paralysis.
Summons a pet at start. This is usually the Ark Angel's Tiger, but can also be the Ark Angel's Mandragora. If killed, the pet is resummoned after 30 seconds.
Tips & Tricks - Sleep the pet and focus on Ark Angel MR. The one having most enmity at the time, will be charmed so plan accordingly (you will get charmed even if the pet is still alive). She does not wait to use Charm, so if you are out of range at the time, you'll avoid it.