Nat& Spectrum System - θ∆

This has been an obsession of mine, but it's also just the broadest you can go without just saying "magic." If we're talking my understanding of shapeshifters, you already have any power in the animal kingdom, which includes flight, super speed/strength/whatever, invisibility (or at least becoming something incredibly small), water breathing, venom, echolocation, asexual reproduction, etc.
Not to mention shapeshifters who seem to be able to become inanimate objects, which basically gives you every power that isn't magic or mind-related (and even then I'm assuming shapeshifting doesn't affect your brain, since becoming a fly doesn't affect your ability to imagine shifting back).