Spell tier
Spell Tiers
The potential power and versatility of a spell is, by design, partially derived from its "tier" on a given guild's spell progression list. The tier of a spell generally indicates how complicated the spell pattern is in terms of in-game understanding, and therefore a higher-tier spell will be harder to cast and harder to put more mana into than a lower-tier spell.
Generally, lower-tier spells have lower minimum mana preparation requirements but take more mana investment to reach their maximum capacity (the spell cap). Higher-tier spells tend to require more mana to power, but require less mana to reach their maximum effectiveness while requiring more Primary Magic skill to reach said cap.
For illustrative purposes, a Tier 1 spell such as the Moon Mage spell Telekinetic Throw (TKT) requires only 1 mana to cast but doesn't cap out until 54 mana, while the Tier 4 Moon Mage spell Partial Displacement (PD) cannot be powered with any less than 9 mana, but only requires 33 to cap out. It requires several hundred fewer ranks of Primary Magic skill to cast TKT at 54 mana, however, than it does to cast PD at 33 mana.
What Tier Is This Spell?
The spell tier of a given spell can be discovered by counting the longest number of continuous spell requirements it takes in order to learn the spell. For instance, the aforementioned Partial Displacement spell requires Teleport, which requires Focus Moonbeam, which itself requires Shadows. Shadows doesn't require any other spell knowledge in order to learn. Therefore, Shadows is Tier 1, Focus Moonbeam is Tier 2, Teleport is Tier 3, and Partial Displacement is Tier 4. If a spell is developed in the future that requires Partial Displacement as a prerequisite to learn, that hypothetical new spell would be Tier 5.
NOTE: The Tier of a spell can only be gauged by the longest chain of prerequisite spells it takes in order to learn it. Even if Partial Displacement also required you to know five other Tier 1 spells, it would still only be a Tier 4 spell. You cannot simply add up the number of total spells you must learn in order to have access to a spell; Spell Tier can only be determined by the longest flow of prerequisite spells it possesses.