Amdapor Keep is hardest Light Party dungeon in the game, having both heavy tank damage and a DPS check. If you are a fresh 50, I recommend you grab some 48+ accessories off the marketplace, running The Wander's Palace a few times, and either buy the Base Relic weapon or try to snag Ifrit's weapon before attempting this dungeon in the Duty Finder.
Clearing this dungeon will reward 100 Allagan Tomestones of Philosophy and 40 Allagan Tomestomes of Mythology.
This encounter will begin with just the Lunatic Priest. Everyone should spread out and dodge the ground indicator for Void Fire II. At 50%, the priest will run near the middle of the room and cast Void Call, summoning Psycheflayer. Finish off the priest while the tank picks it up. You should position this boss over to the right side of the room, near the lantern.
The boss itself will only use three abilities which you need to be aware of. Void Thunder III is its main burst damage. However, the tank can actually move behind Psycheflayer during the cast and cause it to cancel. This is useful if the damage from other abilities starts to stack up and the healer is falling behind. Psycheflayer will also use Mind Melt, which will deal damage to the entire party. Finally, it will cast Canker, placing Disease on a random player. This should be removed, as it snares the player and reduces healing taken.
In addition to those abilities, Psycheflayer will also alternate between reviving two adds, the Stone Marionette and the Marble Marionette. Both of these should be picked up by the tank and killed quickly. While the Stone Marionette is alive, the group will need to dodge Rockslide, a frontal column. While the Marble Marionette is alive, either the tank or a DPS should interrupt the Obliterate ability.
At 50% HP, Psycheflayer will revive a Megalith Marionette at the far end of the room. This enemy does not attack anyone and will walk slowly through the area, occasionally casting Plaincracker. This is where positioning near the lamp comes into play. If everyone hugs the right wall, you'll only have to move a little to avoid Plaincracker. Ignore the Megalith Marionette and continue killing Psycheflayer and it'll drop soon.
This boss drops 20 Allagan Tomestones of Philosophy.
While Demon Wall is lacking in abilities, it makes up for it by being quite unforgiving. Being in the wrong place for Repel will push you off a cliff, instantly killing you. Luckily, Demon Wall will always follow the same pattern. It will cast Liquefy down the middle of the walkway, then down the sides, then in the middle again, and finally down the sides one last time. At this point, Demon Wall will cast Repel. This pattern will continue until the boss is killed.
To avoid being knocked off the platform, it is extremely important to be near the middle of the walkway when Repel is cast. I also found being too close to the boss sometimes will send you off at odd angles. If repel doesn't seem to knock you back, I recommend staying in the middle for a few seconds. Sometimes the effect gets delayed for a few seconds.
After the second Repel, a black pool will appear near the back of the platform, greatly reducing the available space. This will inflict heavy and deal ~400 damage a tick to anyone standing in it.
In addition to the pool, two Bloodlappers will spawn in front of the Demon Wall. Ideally, use a melee limit break on one of them and kill the other quickly. These will use Thunderstorm, which will fill most of the available platform and paralyze anyone caught in it. Stun the cast if possible and don't forget to keep dancing.
This boss drops 30 Allagan Tomestones of Philosophy.
There are two locations you tank this boss. The first is the entrance of the room, which should only be used if you only have ranged DPS. To pull to this position, have most of the party move to the right, then pull the boss straight forward to the entrance before rotating it so that the tail never faces the party. This prevents Tail Drive from ever being an issue. If you have melee DPS, you can also choose to tank him in the back right corner. This allows the tank to avoid moving for Imminent Catastrophe, as well as the melee DPS to still be able to hit Anantaboga during it. The downside to this position is it greatly limits the amount of room you have.
Other than Tail Drive, Anantaboga will use Rotten Breath on the tank, which will deal heavy damage and inflict Disease, reducing healing taken. Unless the tanks health is critical, remove the disease before healing them. Melee DPS should attack from the side to dodge both Tail Drive and Rotten Breath.
Roughly every minute during the fight, the ability Imminent Catastrophe will be used. This will create a large, red orb in the middle of the room during the cast. You will need to hide behind one of the statues to avoid a large burst of damage. Make sure you line-of-sight the red orb, not the boss. If you are tanking in the back corner, the tank does not need to move.
To make this slightly more complicated, each Imminent Catasrophe will awaken one of the statues. These do not need to be tanked and should be burned down quickly by the DPS. While these are alive, make sure you dodge Terror Eye. These will awaken in the same order every pull. From the entrance to the room, the order is the back-left, the front-right, the front-left, and finally the back-right.
After the second Imminent Catastrophe, Anantaboga will begin to use Plague Dance and target a random player with a purple beam. After a few seconds, the beam will fade and a red orb will appear at that players location, dealing damage to all nearby targets. As soon as you are targeted with a purple beam, run to a corner or side of the room. Do not place these orbs near the statue that the group is using to line-of-sight Catastrophe. These balls will vanish after Imminent Catastrophe is cast.
This boss drops 50 Allagan Tomestones of Philosophy and 40 Allagan Tomestones of Mythology.