Pulse is an elemental form of energy, meaning that the universe sees eight different shades of Pulse, eight distinct elements.
Six, not eight. That's going to take a lot of getting used to. We have the Tempest to thank for that. See, there used to be eight elements in four opposed pairs, keeping the balance of the universe: Light and Dark, Stasis and Change, Essence and Resonance, Tide and Vortex. Magic aligns to elements, often one main element with a little hint of a second. Gods are strong in one or two types of elemental energy, often with a minor aptitude for a third.
Then Tempest turned up and one day the elemental pair of Tide/Vortex was gone. Simple as that, like it was sucked from the universe. Gods who'd associated with one (or worse, both) of the pair, found themselves mostly powerless. Magic related to those elements stopped working. It was game over for whole schools of magic. Then the Tempest forces started using Tide and Vortex powers.
You can see why even gods are scared of the Tempest.
Elements Of Matter
I know we're talking about Pulse, but there's another type of elemental magic available. The elements of matter are infused in the spiritual signature of physical objects, and there are six of them in opposed pairs: Air and Earth, Fire and Water, Wood and Metal. Some magic can use Pulse to tap into those elements too. There were never eight of those, and the Tempest doesn't seem interested in magic related to the elements of matter, though nobody's quite sure why.
Gods And Great Spirits
I've been dodging this one, but it seems like the right time to talk about the gods and great spirits. Beings of divine power are defined as those who live in the Maelstrom beyond the Veil and who are so powerful that they can shape the clouds of raw Pulse into permanent constructs. They use this ability to craft god realms for themselves. This is great because they make such a mess of the mortal realms when they cross the Veil that they all have an agreement to stay away. It has a lot to do with Zeus and that whole "swan seduction" thing. Really, he should be ashamed of himself, but who's going to say that to his face?
Groups of heroes have been known to create small pocket realms for themselves in the Maelstrom, but they're not permanent. If the heroes leave for long enough, the realm collapses. Not so for the gods and great spirits. Their realms survive even their death - yeah, gods and great spirits can die. It's just rare that death sticks for a being of divine power.
The difference between gods and great spirits is pretty minor. Gods group together in pantheons, each god or goddess with their own roles. Zeus the lusty lovebird is the sky god and head of the Greek pantheon on Mount Olympus. Hera is his wife, the goddess of hearth and home. Artemis is the goddess of the hunt. And so on. It's the same pattern for the Norse, Egyptians, Chinese, Mesoamericans, and even the archangels who have their own realm.
Great spirits are loners - each is the incarnation of a single idea, and they can get pretty weird (as weird as the shared human imagination which created them). There's a great spirit of dragons, of love, of hate, order, the color red, and many other things besides. Most have created a realm for themselves somewhere in the Maelstrom. Some of those realms are… special.