Deal the killing blow on Anamor Grintooth.
Preparation: have underwater breathing and/or bubble cluster equipped prior to entering the area. Create an alias to remove and re-wear your UB/BC item quickly. Standard preparation required, including reagents and mems, etc. Be visible for the mark. The room is private, so you can tag-team or solo it. It is definitely soloable by a solid archon with good AR. The rooms leading to him are LPK and his room is NPK, so you can wear good gear for this fight.
Instructions: From Darksea recall, go east, northeast, east, southeast and northeast into Grintooth's room "Deep Within the Reef". He does not aggro. Spell him up as normal, but note that each time you use a spell he will reduce your knowledge of that spell by 10% for a short duration of time. You can backstab him down a bit in the beginning, or just bash/flee every couple of rounds.
Special Note: Grintooth will randomly do a cyan emote that will remove your underwater breathing & bubble cluster affect, and force you to drink up to 19 mouthfuls of water. If this happens, it will kill you on the next instantly. To prevent your impending death, flee immediately southwest and run back to SAFE. Remove/rewear your underwater breathing / bubble cluster and check your SCORE to see how many mouthfuls of water you drank. You must wait at SAFE until you no longer have consumed any water - the mouthful counter will decrease quickly over a tick or two. Then return back to Grintooth, and repeat.