The Octulhu is 1 out of the 4 possible events that can happen every 30 minutes.
It's similar to a mini Archdemon if you've experience on that.
It's about the same octulhu's you can find in regular astral sailing, but with better loot.
The Octulhu is a standard demon, and like any demon, you can use its weakness to your advantage.
For that, have your visor target the demon. Once targetted, it's not required to have a player stay on the visor.
It's going to rotate through 2 weakness, seen on the visor. Whatever is active at the time, makes him take more damage from those cannon shots.
Artilleries do not affect these.
Once the Octulhu is killed, chests are spawned on the topdeck immediatly. So there is no need to "incubate" the chests as you do with the 3 other events.
The Octulhu does have a fixed loot tho, so there is no measuring as in how fast you can kill it or how little damage you take.
It always 2 chests.
Each chest has 5 Particles of Anomalous Matter, your weekly Spark for Anomalous Sector and a random Ship Device of Epic Quality.
The Octulhu gives the most Particles per event, and is a great way to get the best ship gear next to Archdemon Legendary quality drops.
Other events can give as many as the Octulhu, but only if you reach the maximum rewards conditions. The Octulhu only needs to die, making it a very good event to do.