Fusionism

Fusionism is the ability to merge something with other things such as people, objects or even abstract ideas to create something completely new.

This can be used to fuse different weapons to create a stronger weapon, fuse people or animals to create new creatures, fuse yourself with the environment or objects to gain new abilities, it can even work to fuse even different concepts or abstract beings together as long as the ability is explained.

Limitations

This ability has potentially a very wide range of uses, however it also has very general limitations, such as being bound by a time limit, not being able to control what you fuse, or being useless if you fuse 2 wrong objects that do not work together or are incompatible.