The Embryon boss fight has three stages. All throughout the fight, the head is able to be destroyed, but it will regenerate; still, it is advisable to do so at times in order to limit the number of attacks on-screen.
The first one starts with four arcs of five fireballs that spread out, five times in total. In Zone Y, the blue variant's head will then jitter before firing a sweeping arc of diamond bullets; in Zone Z, the red variant will not use an attack here, but it comes at the end of the pattern. Both variants will next release enemies to capture as it travels along the bottom of the screen while spraying normal bullets after the player followed by circles of diamond bullets, ending as it reforms into an octahedron shape. As the head fires rainbow helical lasers while tracking the player as well as anchor projectiles, the core will release Eclipse Eye debris that is destructible but which does release an arc of five diamond bullets if destroyed. After reforming into the full sea angel form, the red variant's head will jitter before releasing a tight sweeping arc of straight lasers. From this point, the pattern repeats from the start until the core has taken enough damage, at which point the boss disappears.
Between patterns, the boss will take an animal shape and head into the background, releasing some waves of large Solidnite shells to move between or destroy before coming back into the attack plane.
The second pattern shows a number of differences in attack type between the two variants, but eventually the head will charge a Beta Beam and fire it, then while it's on-screen, the core will fire a Counter Beta Beam. Assuming this is properly countered, the boss will disappear during the Double Counter Alpha Beam and it will need to expire before the Solidnite shells can be destroyed or dodged. The third and final pattern also shows marked differences between the two variants, and the timing to finish them also differs. The red variant will see both the head with a Beta Beam and the core with a Counter Beta Beam in the octahedron form for the player to counter. The blue variant will have only the head release a Beta Beam, and when it reforms to the sea angel shape and turns all about, the core will fire a Counter Beta Beam with a rainbow cube capture shot out right before it. In either case, the boss should fall here.
Cameo in Dariusburst
In the Zone J ending to the original Dariusburst, when the Syvalion is destroyed, The Embryon shows up to hearken another coming of the Thiima. Ti2, having a connection to them, heads in with the aim to negotiate the safety of the people of Darius and all of mankind while Riga Practica stays behind to wait for her. The ending changes in the SP Mode for Zone Y in Darius Burst Second Prologue, as when The Embryon shows up to the pilots, it stays in place as if to study and observe the four of them and their Silver Hawks. After what seems like a very long time, The Embryon and the Thiima leave after silently deciding to spare them and mankind as a whole.