|Primary Biome||Open Seas|
|AI Type||Dragon Boss|
| Deep Sea Dragon Egg Fragment|
Thallasion is a large World Boss that spawns rarely in Open Seas biomes. When defeated, it drops several Deep Sea Dragon Egg Fragments based on the difficulty of the world, which can be used to craft Thallasion, Shaper of the Currents at the Dragon Crucible.
Like other dragon bosses, Thallasion has significantly more health and damage compared to dungeon bosses in the same difficulty, meaning it's best approached with a group of players at the matching power level.
As Thallasion naturally spawns underwater, fighting it may become more difficult as the players' movement and attack speed will be reduced.
It can perform three attacks:
- Bite: Thallasion lunges out and bites a nearby player.
- Tidal Wave: Thallasion jumps up and flaps its wings to do an aerial attack to a nearby player.
- Acid Spread: Thallasion roars and sprays acid projectiles into the air. The projectiles will target a nearby player and drop a 2x2 block of acid, which can then flow further outwards. This acid will harm players in the block (very similar to lava blocks) and heals Thallasion on contact.
The number of Deep Sea Dragon Egg Fragments dropped varies based on the difficulty Thallasion is defeated in:
- The boss is massive in size, so it is easy to spot.
- Thallasion grants experience depending on the world you are in and drops 2 pieces of gear and the appropriate amount of Key Fragments of that world (very similar to the loot of a Lair Chest).
- Thallasion can also spawn in rare Dungeons representing large mounds of sand in the Open Seas; destroy the blocks downward to go directly to a room with Thallasion.
- Despite being similar to a dungeon, with set terrain and a quest popup, it does not appear on the map, nor does it have any monsters or bosses except for Thallasion.
- Thallasion can also spawn in a variant of the Open Seas, which appears much darker than usual on the map and has a single guaranteed dungeon with Thallasion.
- This enemy uses most of the same model as the mount Dracocolatl, the Mellower, except for one part (c_mt_dragon_deepsea_body_03, changed to c_mt_dragon_deepsea_body_03alt) to remove the saddle the mount uses.