Ability to combine creatures AND elements to create new forms of life have some elemental effects with the possibility of releasing them into the wild to reproduce (again reasonably)
This would create a new set of creatures created by the player to enhance or degrade their play through. Some things can be positive like enhanced nutrition or negative effects like poison bleeding, raging hunger, and connected static electricity. The elements part can be tricky but mostly want to create new creatures with random effects based on what you combine.