Limited Spell Levels (3.5e Variant Rule)

Limited Spell Levels
Spellcasting can often be seen too strong at many levels of the game. This variant tries to curb that power to some extent by slowing down the progression of spell levels that casters have access to.

While the number of spells per level and spells known of a class are unaffected by this variant, casters are limited to the level of spell that they can prepare or cast to a number equal to one-fourth the number of class levels they possess in classes that grant spellcasting (rounded up), as per the following table:

Note that this only affects the maximum level of base spell prepared or able to be cast (for sorcerers). Wizards may use higher-level slots to place lower-level spells (including metamagic version of lower-level spells) while sorcerers may do the same with their spontaneous slots. Wizards may still scribe higher-level spells into their spellbook for later use, and sorcerers still follow the normal progression of spells known, but cannot prepare or cast such spells respectively.

Thus, a level 13th level wizard (who has access to 7th level spell slots, but can only know a maximum 4th level spell) could prepare a Maximized Fireball using their 7th level spell slot, but would be unable to fill it with Delayed Blast Fireball which is a 7th level spell.

Since Greater Dispel Magic is out of the reach of most casters under this variant, it becomes a 4th level spell for those who would have it at a higher level, while Dispel magic becomes a 2nd level spell for those who would have it at a higher level.

Adaptation
This variant can easily be adapted to other curves of power. If a DM feels that 4th level spells are the limit of the power that they want to venture, then they might make the variant limit to a spell level every 5 caster levels. On the other hand, if they want to max 6th-level spells the maximum, they might make it every 3 caster levels (but rounded down, or rounded up but capped at 6th level spells).