its technically like 5 or 6, but half of those are extremely infrequent, like only pressing them once every 30 seconds to a minute.
you’ve got consume, which is like your frostbolt equivalent, a basic hard cast that generates fury and souls. reap is a 8 second-ish cd that deals some damage and collects souls (they sit on the ground, kinda like soul fragments in other DH specs, reap vaccuums them up). you’ve got voidblade which is a 30 second cooldown attack that deals some damage and generates fury. those are your basic rotation and generators
then you’ve got void ray, which is your eye beams, which require 100 fury (about 10-12 hard casts of consume worth of fury, though you have other generators for fury too), and metamorphosis which requires 50 souls (consume generates 1 soul per cast). metamorphosis then unlocks another spell called collapsing star which is a big nuke and the goal of the whole rotation
i kid you not i finished an entire questline the other night without ever amassing enough souls to actually enter metamorphosis. its a very bad spec, and you will be spending a lot of time in the worst aspects of it. the rotation takes so long to get going it would be quicker just to sit through a talent respec to havoc and cast metamorphosis that way than try to actually build up devourers metamorphosis.
oh and to make matters worse, their mastery and probably half the talents in the tree all revolve around metamorphosis, so all of your talents and mastery do nothing until you hit that full buildup of souls
there is also soul immolation, a confusing ability which lights yourself on fire causing you to take damage over time but generates some souls and fury in return. like vengeances immolation aura except you take the damage, not the enemies. very strange. i will say, after some testing, the default talent choices will set you with spontaneous immolation, which deletes the soul immolation button and replaces it with a passive 5% chance for that effect to trigger on spellcast. i found this to be a trap. its proc rate is too low, you need soul immolate to rev up the engine but this ability doesnt proc easily on your basic rotation, but rather in your more advanced spenders, so its like you lose out on that ignition primer. take tempered soul instead and use it often, the spec is almost playable with that