Tablet of Atlantis
Tablet of Atlantis - Artifact
For basic info on this encounter see: http://www.visionofsages.net/toa/artifacts/atlantistablet.html
Go to 43794, 58839 Meso and drop a ground target with your Shaman. This is where you are going to heal from later and you want to get back to this spot quickly. From here you can heal inside the temple without getting guard aggro. Make sure you are ungrouped.
Cast a pet and buff it up. Put it on Passive and use Go Target to send it at one of the guards. While the guards are pounding on it, run inside the temple and swim up to the roof above the chests, avoiding any leftover mobs if they're there. If the pet does no damage to the guards, they won't come after you once the pet is dead.
Drop a power font. If there are any leftover Guardians of Atlantis, you can kill them, but if you open the right chest, they will despawn, so I just leave them up. If any are there, you'll need to summon a pet and send it in to run interference for you as you open the chests. Now send in the SM to open a chest. If it's the wrong one, you'll die to a big blast and a triton agaeus will pop. Rez quickly and immediately send the SM back down to be killed by the agaeus, who will then disappear. Repeat this until you find the chest with the Guardian of Atlantis in it and die to it too.
Now you're working against the clock - the Guardian of Atlantis is going to despawn in a few minutes and you'll have to do the chests all over again. So get the SM up fast and put up a spirit fighter pet. Only buff the pet - buffing the SM is just a waste of time. Now go down to 43629, 60503 making sure to stay safely between the Guardian and the guards at the door. Put a groundtarget between the guards and drop a Battlewarder. The guards will aggro on it giving your bot time to get out. Put him on the groundtarget you laid earlier for him and drop a power font.
Target the Guardian and use Passive and Go Target to send the pet to it. As soon as the Guardian aggros, put the pet on Passive and Here. You want the pet standing right where you're standing but not hitting the Guardian. Put up your focus damage shield if you haven't yet. Now it's just a straight focus kill.
The Guardian hits pretty hard, but pretty slow, so you can keep up with healing with no power problems. Heal to your heart's content - the shaman is safe outside the temple. I've only had one split when the pet was on Passive in the 3 times I've done the encounter. If you're standing at the location above, the splits will stay in the center of the room and not aggro the pet - they'll just stand there healing themselves but not the Guardian. The Guardian goes down in about 5 minutes. The only time the focus shield didn't work on her was when she said she was weak to body. During that period, the shield did no damage - so when you see that message, feel free to sit down to conserve power. During the fight she also said she was weak to slashing, thrusting, crushing, matter, cold, energy, and heat and the shield still worked fine.
If you got any splits, it's kind to clean them up before leaving since they don't despawn on their own for the next person.
The Tablet is not a guaranteed drop.