To address your situation with the boss animation that has different phases and requires changes in sprites within those phases, you can utilize the concept of skin placeholders within Spine. Each phase of your boss (phase1, phase2, phase3) can be represented by a different skin. Within each skin, you can create skin placeholders for the parts that change, such as the "Mouth" and "Hands".
For the "Mouth" slot, you can have skin placeholders like "OpenMouth" and "ClosedMouth" within each skin (phase). This allows you to switch between "OpenMouth" and "ClosedMouth" for each phase by changing the visibility of these skin placeholders in your animations. The same approach applies to the "Hands" or any other part that changes between phases.
This method does not assign complete slots to skins directly but allows you to manage different states (like "OpenMouth" and "ClosedMouth") within each phase by using skin placeholders. This approach provides flexibility and keeps your animations and skins organized.
Remember, slots are used to define the draw order and are independent of skins, but you can have multiple attachments (or skin placeholders) within a slot for different skins. This setup allows you to switch between different states or appearances of a character part within the context of a skin (or phase, in your case).
