Energy is an omnipresent thing that exists in an infinite amount across the Omniverse. It is primarily defined as a quantity necessary for performing mechanical work, but it exists in many forms. In particular, it makes up all particles of matter, and is the most basic force behind all life in the Omniverse.
Having limited space, universes usually contain a preset and finite amount of energy, but it is possible to import or export energy from the local multiverses, which almost always contain infinite amounts of it. Certain universes that are infinitely large often contain infinite amounts of energy.
The law of conservation of energy states that it is impossible to create or destroy energy in the Omniverse. What this means is that there is no method to cast energy from nowhere; anything that appears to generate energy, such as magic, actually draws it from the Omniverse. There are a few air conditioning units that take in heat and expel it back into the Omniverse in order to make the surrounding environment cooler.