PolyMixin is a Mixin library that extends a mixin's target list at runtime. Put @DynamicTargets on a mixin and it gets applied to every subclass of the class it targets, including subclasses that ship in somebody else's mod, without you naming any of them. Further target modification is configurable.
Supports Forge 1.20.1, NeoForge 1.21.1, and Fabric 1.21.1. Further support may be implemented in the future. (Likely out of the box compatible with most, but I am too lazy to test right now)
Thank you to Leclowndu93150 for completing this commission!

