You can safely skip the first part of Atlantis II once you complete Atlantis I. The first quests are for acquiring the Underwater Map, Eye of the Kraken, and Kraken's Tentacle. These items are used to summon Kraken and Alpha Kraken from which you need to acquire Relics of the Kraken.
Instead, you can choose to fight Alpha Krakens that are Public monsters, and obtain the necessary Relics of the Kraken. No are not required to do the quests and summon Alpha Krakens yourself. Additional Skill Points are available if you do these quests and obtain maps, eyes, tentacles, and Horns of the Sea, if you wish.
Fighting Alpha Kraken, you need to do 4 million damage to get one epic drop, and 7.5 million damage to get two epic drops. Relics of the Kraken drop at about 40% chance per epic drop. Fighting about 10-12 Alpha Krakens at 7.5 million damage each should get the 9 Relics of the Kraken you will need.
- Level 1 requires 1000 Energy and drops 1 Horn.
- Level 2 requires 3000 Energy total (1000 for level 1 and 2000 for level 2) and drops 2 Horns.
You need a total of 5 Horns of the Sea to initiate the last quest, Underwater.
Having 9 Relics of the Kraken allows you to start 3 Path Quests, where you should do at least 2 Path Quests to level 2 in order to get the 5 Horns you will need.
The Underwater quest is difficult. You will need to acquire:
This quest should be completed to at least Level 5, as this is the MINIMUM required for Elder Scrolls to drop. Completing Level 6 assures you of 1 Elder Scroll. You can get lucky and get the same drop with level 5 collection as level 6 collection.
You will need a total of 8325 Energy within 120 hours to get to collect at level 5. Generals such as Hyacinth, Godric, Theorin, or Ambrosia can be helpful here, since natural regeneration (2,880 over 5 days) alone is insufficient. To get the rest, either increases in level, or refilling Energy with Favor Points will be necessary. A natural stat of ~1200 Energy can suffice if you plan on refilling twice in 5 days for each quest.
The expected drop from level 5 is 2 brilliant/1-2 mystical/0-1 elder scrolls, so expect to do the quest ~12 times to collect enough Mystical Scrolls.
You will need to create Krakenhide Armor (2 brilliant/7 mystical/2 elder) in between, then ANOTHER Krakenhide Armor, then get the helm with 2 more brilliant/4 more mystical/2 more elder scrolls and 2 Krakenhide Armors.
Timeframe? 12 Underwater Quests is 60 days time. Expect 70-90 days time for the whole process. It is no small undertaking!