Beyond Sosaria layers a roster of custom spell systems on top of the standard Ultima Online magic schools. Custom spellbooks and scrolls are issued primarily as boss and town invasion loot.

===== Spell Systems =====

==== Custom Schools ====

The custom engine adds the following schools: Magery, Necro, Chivalry, Ninja, Samurai, Druid, Avatar, Bard, Cleric, Ranger, Rogue, Undead, Ancient, and Archmage. Spell restrictions are enforced: casting a custom spell requires the matching spellbook to be equipped, carried in the backpack, or stored inside a Sosarian Tome.

^ System ^ Cast Skill ^ Damage Skill ^ Spellbook ^
| Archmage | Magery | Evaluating Intelligence | Archmage Spellbook |
| Avatar | Chivalry | Focus | Avatar Spellbook |
| Bard | Musicianship | Musicianship | Bard Spellbook |
| Cleric | Spirit Speak | Evaluating Intelligence | Cleric Spellbook |
| Druid | Animal Lore | Animal Taming | Druid Spellbook |
| Ranger | Archery | Tactics | Ranger Spellbook |
| Rogue | Stealing | Hiding | Rogue Spellbook |

==== Archmage ====

  * **Cast Skill:** Magery
  * **Damage Skill:** Evaluating Intelligence
  * **Spellbook:** Archmage Spellbook
  * **Content:** Extends Magery with Ninth and Tenth circle spells. The Ninth circle adds 5 spells. The Tenth circle adds further high-tier spells including Apocalypse, Cosmic Strike, Hellfury, Shockwave, and Tornado. The system also bundles an Archmage Staves system.

==== Avatar ==== 
-- Not Currently Accessible.

  * **Cast Skill:** Chivalry
  * **Damage Skill:** Focus
  * **Spellbook:** Avatar Spellbook
  * **Spells:** Heavenly Light, Heaven's Gate, Mark of Gods.

==== Bard ====

  * **Cast Skill:** Musicianship
  * **Damage Skill:** Musicianship
  * **Spellbook:** Bard Spellbook
  * **Spells (16 total):** Army's Paeon, Enchanting Etude, Fire Carol, Ice Carol, Energy Carol, Poison Carol, Fire Threnody, Ice Threnody, Energy Threnody, Poison Threnody, Foe Requiem, Knight's Minne, Mage's Ballad, Magic Finale, Sheepfoe Mambo, Sinewy Etude.

==== Cleric ====

  * **Cast Skill:** Spirit Speak
  * **Damage Skill:** Evaluating Intelligence (inherited from the base spell system)
  * **Additional requirement:** Cleric spells require Tithing Points ("Piety") in addition to mana and skill.
  * **Spellbook:** Cleric Spellbook
  * **Spells:** Angelic Faith, Banish Evil, Dampen Spirit, Divine Focus, Hammer of Faith, Purge, Restoration, Sacred Boon, Sacrifice, Smite, Touch of Life, Trial by Fire.

==== Druid ====

  * **Cast Skill:** Animal Lore
  * **Damage Skill:** Animal Taming
  * **Spellbook:** Druid Spellbook
  * **Spells (16 total):** including Grasping Roots, Volcanic Eruption, Spring of Life, Swarm of Insects, Stone Circle, and Shield of Earth.

==== Ranger ====

  * **Cast Skill:** Archery
  * **Damage Skill:** Tactics
  * **Spellbook:** Ranger Spellbook
  * **Spells:** Familiar, Fire Bow, Hunter's Aim, Ice Bow, Lightning Bow, Nox Bow, Phoenix Flight, Summon Mount.

==== Rogue ====

  * **Cast Skill:** Stealing
  * **Damage Skill:** Hiding
  * **Spellbook:** Rogue Spellbook
  * **Spells:** Charm, False Coin, Intimidation, Shadow, Sly Fox.

==== Standard Schools ====

These schools are active alongside the custom systems.

^ School ^ Cast Skill ^ Damage Skill ^ Spellbook ^
| Magery (1st-8th Circle) | Magery | Evaluating Intelligence | Spellbook |
| Necromancy | Necromancy | Spirit Speak | Necromancer Spellbook |
| Chivalry | Chivalry | Chivalry | Book of Chivalry |
| Bushido | Bushido | Bushido | Book of Bushido |
| Ninjitsu | Ninjitsu | Ninjitsu | Book of Ninjitsu |
| Spellweaving | Spellweaving | Spellweaving | Spellweaving Book |
| Mysticism | Mysticism | Imbuing or Focus (whichever is higher) | Mystic Book |
| Skill Masteries | Per-mastery primary skill | Per-mastery skill | Mastery primers / Book of Masteries |
| Gargoyle (Flight) | n/a (racial) | n/a | -- |

Spellbook types available: Regular, Necromancer, Paladin, Ninja, Samurai, Arcanist, Mystic, and Skill Masteries.

===== Acquisition =====

Custom spellbooks (Archmage, Bard, Cleric, Druid, Ranger, Rogue) drop with a 20% chance from Warlord-class town invasion bosses, with one of the six chosen uniformly at random. Custom books may also be stored inside a Sosarian Tome, which lets spell restrictions resolve against books stowed in the tome instead of the open backpack.