Meet the Yin Yang Twins:
and Yang Chicken
Bosses have 2 phases, and they appear rather strangely…
Phase 1: Yang appears in the upper left corner and Yin appears in the lower right corner.
Their attacks are spinning around the screen similar to Twice Infinity, but they do it constantly and lay eggs at the same time!
Each of the twins has 25% of life, i.e. after defeating them it reaches 50%.
(The defeated twin does not die, but flies to the middle and waits for his brother)
When the twins are defeated and reach 50%, they fly to the middle and…
They become one!
Phase 2: Yin Yang Chicken is in the middle and summons a black and white portals around him which spinning.
The diameter of the spinning portals will increase and decrease, in this form the twins no longer lay eggs.
Thanks again @Darth_Skembesion, this time he changed the models of 2 big chickens to white and black, but I made a fusion.