@Heartz13 I voted for cosmic energy, because of what you just said: interdimensional energy may be sourced from and behave in accordance with a reality with physical/metaphysical laws and properties that are radically different from those of our own reality. The effects of its mere presence, let alone use, in our universe is completely unpredictable. Interdimensional energy could possibly be inert, incredibly powerful, dangerously chaotic, or existentially volatile within our own, and there’d be no way of knowing which it really is until using it, by which point the user may have done some serious, possibly irreversible damage.
Not to mention, cosmic energy is nothing to scoff at. We’re talking about the kind of thing that powers the likes of Superman and Galactus. Cultivating it is likely to afford spectacular powers, powers which act on and conform elegantly to the fundamental forces, parameters, and constraints of our own reality. One might see that as a limitation, and it is, but it’s worth considering that in this case such limitation in some sense maximizes the effectiveness of the power.