This mod adds incantations for master spells. Incantation spells are %25 more powerful but requires 75 speechcraft. After completing the Ritual Spell quest for any school, you can visit Aran Magius in the Midden first level where the conjuration area is. He'll provide one of the master spell incantations. You can purchase the others from related trainer afterwards for 2000 gold. Incantations are simply latin sentences commanding to create the effect. Here is the list of them :

-- DESTRUCTION --
fire storm >> ego creo ignis tempestas! - I create a fire storm!
blizzard >> ego creo nivis tempestas! - I create a snow storm!
lighning strike >> ego creo fulgur tempestas! - I create a lightning storm!

-- RESTORATION --
bane of the undead >> inmortui! fuge mortem tuam! - undead! flee for your death!
guardian circle >> inmortui! praeclusus es! - undead! you are blocked!

-- CONJURATION --
conjure flame thrall >> ego obtestor flammam servi! - I conjure a flame servant!
conjure frost thrall >> ego obtestor nix servi! - I conjure a snow servant!
conjure storm thrall >> ego obtestor tempestas servi! - I conjure a storm servant!

-- ILLUSION --
call to arms - ego benedicat comitibus meis! - i bless my companions!
harmony - ego praecipio tibi ut desinas! - i command you to stop!
mayhem - ego praecipio tibi ut pugnare! - i command you to fight!
hysteria - ego praecipio tibi ut fugere! - i command you to flee!

-- ALTERATION --
dragonhide - ego sum draco! - i am a dragon!
mass paralysis - venenata sunt verba mea! - my words are poisionous!

You can see a demo here :
https://www.youtube.com/watch?v=PNFukIVYHGQ&ab_channel=CuneytTyler

Enjoy!