Most of these spells are based on the official Storm of Magic book. However, where this isn't possible I have tried to design thematic spells to fill the gaps.

• Command the Winds gives the casting Lord considerable spellcasting powers for one minute, including more winds of magic, cooldown reduction, and near immunity to miscasts. This is a deviation from the book which would have been tricky to transcribe into the game.
  
• Hymn of Agony is a self tool that empowers the caster at the cost of enemy life force. This is a take on Power of Darkness.
  
• Malediction of Nagash is almost directly copied from the book, and reduces enemy strength by half in a wide area. The alternative was The Army of Doom Keep, but vampires get enough summons as it is so it didn't feel as exciting.
  
• Tzeentch's existing skill tree already encompasses powered down versions of the cataclysm spells from the book (namely Blue Fire of Tzeentch and Tzeentch's Firestorm). To this end, I used Dispel Mortal, a spell from the general chaos pool.
  
• Kairos, being the master of magic that he is, also gets a fun (albeit not terribly cataclysmic) spell based on the swing of a pendulum. Pendulum of Fate was suggested by Helios (thanks!) and is a 'bonus extra' for fun and flavour.
  
• Rotbomb is another lore-friendly spell from the book, which strips enemy armor. However, given how many spells do this already, I added a decent DoT to this spell as homage to Grandfather Nurgle's Circle of Life (the other cataclysm spell in the book).
  
• Slothful Stupor is another lore-friend spell from the book, and causes enemies in the area to become increasingly slothful and less willing to fight as they linger.
  
• Khorne despises magic, and tends to hurl giant skulls at casters who invoke incantations in the name of his brothers. With that said, a big skull nuke didn't feel terribly exciting, and so I've opted to provide the ability for Khorne factions to call upon one of their biggest, angriest, most skull-loving allies - the Soul Grinder. Unlike other summon spells, this does not have a duration before unbinding, to reflect its cataclysmic nature.
  
• Warpstorm is a lore-friendly Ruin spell, which largely mimics the effects of Thorsen's Thunderstorm. While each bolt does less damage, it hits a wider area with more bolts overall.
  
• The Great Red Pox is a lore-friend Plague spell. This spell creates a huge area of effect which slowly poisons both friend and foe (in typical Skaven fashion). To ensure this is not just used from half a map away, the caster must be close to the drop zone and will undoubtedly end up poisoning themselves too!
  
• Kislev has no presence in the book and so this is a new one. Although Ursun's Indomitability is the ice-themed cataclysm spell, it suits Kislev's playstyle as a whole and so has been - at least temporarily - adopted by Mother Ostankya. While this spell adds leadership, I wanted to avoid unbreakable as the Kislevite passive provides this already.

Some Lords cover multiple lores of magic, but perhaps lack the magical knowledge (lorefully) to wield multiple cataclysm spells. Also, given the power of these spells, dual-casters should be limited only to the most exceptional of spellcasters.

• Malagor the Dark Omen is a tricky one. While Lore of the Wilds does get its own cataclysm spell in the book, Dance of Despair leans beautifully into his theme as a harbinger of doom, and so I opted for this instead.
  
• Malekith gets Shadows because of his role in the End Times as the Incarnate of Ulgu. Given Malekith's role as a hybrid unit, I didn't want to give him a second cataclysm spell (likely Hymn of Agony), although this might change in the future.
  
• Balthasar Gelt does get Gehenna's Golden Globe via this mod, which stacks on top of the one he gets from his arcane essay mechanic. I intentionally did this so as not to detract from his campaign mechanic.
  
• Wurrzag da Great Prophet has Merciw's Monstrous Regiment. Big Waaagh! spells already have decent coverage in the game (through Foot of Gork), and it didn't feel worthwhile designing a specific cataclysm spell just for Wurrzag.
  
• Teclis gets two cataclysm spells, to reflect his position as one of the most powerful casters in the Warhammer universe.
  
• Eltharion the Grim picks up Time Amok here, as I wanted to reserve the High magic cataclysm spell for true spellcasters. This may change in the future.
  
• Mazdamundi gets two cataclysm spells, as he is the most powerful (living) Slann priest. This also compensates for Ruination of Cities which is lacklustre.
  
• Skrag the Slaughterer gets Merciw's Monstrous Regiment. Ogres do get cataclysm spells (Feast of the Fallen and The Great Maw Awakens), and so this may be a future project.
  
• Grand Hierophant Khatep gets Time Amok. While Nehekhara does offer Return of the Golden Age, this only gives map-wide damage buffs and didn't feel terribly exciting as a big button ability.
  
• Cylostra Direfin gets Hymn of Agony, to fit with her opera singer theme. Although this is the Dark Elf lore, it didn't feel worthwhile designing a Deeps spell just for her.
  
• I hate Mannfred. He gets Death instead of Vampires because he's dead to me.
  
• Archaon the Everchosen gets two cataclysm spells, although this may change in the future given that he is already proficient in melee and - lorefully - is not an immensely powerful caster (compared to others, at least).
  
• Mother Ostankya picks up Ursun's Indomitability. Although this is the ice spell, it is more of a general Kislevite lore and doesn't clash too much with the lore of Hags. The alternative here could be Merciw's Monstrous Regiment to lean into her army of the wilderness theme.

I am not terribly beholden to the lore, and have made some creative changes where it seems to fit. However, I am always happy to accept feedback about the spells themselves, as well as the choice of lord (particularly if some spells are over or under-performing, or aren't 'fun' to use). I might not make every change suggested but I certainly will read them all.