Summary
Though older versions refer to them as Fusion Spells,Persona 3 Reloadhas completely repurposed the series of powerful attacks your protagonist could use as they fused more powerful Personas. And while you used to need to keep all these Personas in your stock, thankfully, having them in the Compendium is enough in P3R.
With seven Theurgy skills for your protagonist to learn as you climb Tartarus, level up, and fuse better Personas, it can be tough to choose which skill to lean for when your Theurgy gauge has maxed out, but here’s our hierarchy of our protagonist’s Theurgy skills.

Apsaras
Priestess
The very first ofyour protagonist’s Theurgy skillsonce the concept is introduced, Cadenza is a helpful support skill for the party, but it’s not often our protagonist serves as our primary healer. With both Yukari and Ken more than capable of handling whatever ails the party, your protagonist is better used to deal outright damage.
That’s not to say there’s never a use for Cadenza, though. Between Full Moon Shadows, the Monad Passage Shadows, Gatekeepers, and more, you’ve got your work cut out for you in the battles ahead, and who knows what’ll happen to your healer. Having a backup option to heal the party doesn’t hurt, but it’s definitely not the skill we use the most.

Decarabia
Fool
The second of your protagonist’s two supporting Theurgy skills, Best Friends unlocks a bit later on into the game and is a powerful boost if you time it right. If another teammate has their Theurgy skill ready to go and you’d like to deal some additional damage with it, or if you have a tough Shadow on the ropes and you just need one more good push to defeat it, Best Friends isa good choice.
But again, this Theurgy skill for our protagonist lands more in a supportive role than keeping him front and center in the action, where the rest of his Personas and Theurgy skills suggest he ought to be. Still, Best Friends can be the difference between ending a fight on your chosen ally’s next turn or dragging it out a bit more, risking damage to the party in the process.

Jack-o'-Lantern
Magician
Almighty damage has always been impossible to block, and the Jack Brothers attack showcases a short comedy routine between the two Shadows that deals a medium amount of Almighty damage. It’s not only a good fallback for Shadows who don’t have weaknesses, but with a decent chance to Down an enemy, allowing for a follow-up attack, Jack Brothers earns its keep.
As a multi-target move, this chance to Down applies to every Shadow on the field, but even one will grant you a One More attack that can turn the tide of the battle. If you’re ever cornered in a multi-Shadow battle, Jack Brothers can be the ace up your sleeve to down otherwise tricky foes.

Satan
Judgement
As the last Theurgy skill you’re likely to unlock, what with Helel and Satan both high-level Personas that require additional steps before you can fuse, it may be odd to see Armageddon place in the center of our best Theurgy skills list. Ultimate Almighty damage can be an absolute killer in battle, but the cost of using the skill can be a bit too high sometimes.
Upon use, your protagonist immediately loses all their HP and SP, dropping to a mere single point in each category. Normally, Ultimate Almighty damage is enough to kill most Shadows, but if you’re fighting a super-tough Shadow or you’re playing on Merciless difficulty, it may not be enough to KO the entire team of foes. Leaving your protagonist at such low healthleaves him at risk for KOhimself, and the last thing we want to do is restart tough battles all over again.

King Frost
Emperor
Any Theurgy skill that starts with our protagonist getting bonked out of the way by the colossal belly of the enormous King Frost is good in our book, but King and I has more than just a fun animation to solidify its place in our list. With heavy Ice damage to all foes on the line, it’s a pretty good way to deal some blanket elemental damage, especially if our foes are weak to Ice.
But not only does it deal heavy damage to everyone, King and I also has a medium chance to inflict Freeze on any foe it hits, leaving them frozen solid and incapable of moving on their next turn, if not longer. This can be helpful when the enemy Shadows are relentless, offering some breathing room in battle to recuperate while they thaw out.

Mithras
Chariot
This may very well be the first of the more powerful damage-dealing Theurgy skills you unlock for your protagonists, with the two requisite Personas pretty easy to come across in Shuffle Time, but the damage they deal is severe – literally. After a duo-power animation, bandsaws slice through the battlefield, dealing severe Slash damage to all foes.
Having a severe-level attack that hits all foes is a powerful tool to have at your disposal, as plenty of Personas top of with heavy damage to all foes. There’s nothing wrong with that – it does the job in most situations – but why not crank that damage up another notch and deal even more to every Shadow on the field?

Susano-o
In previous versions of Persona 3, this move would cost your protagonist a staggering 15 percent of their SP to use, but thankfully, Persona 3 Reload has moved the Trickster skill over into our Theurgy moves, and we couldn’t be more excited. The only thing better than dealing such good Almighty damage (that can’t be protected from) is doing so while inflicting a status ailment.
Trickster not only hurts the enemies, but it stands a really good chance at leaving a lingering effect behind. Any status ailment inflicted on an enemy can quickly sway the battle in your favor, so provided the other side survives the attack at all, they’re not long for the battle after, depending on which status ailment they ended up with from the Trickster Theurgy skill.