Magic functions a little differently in some aspects within the World of Amastasia. These changes reflect some influence from the Pathfinder Game System™ as well as personal opinion to some of the mechanics found in the Dungeons & Dragons™ 3.5 edition rules.
Casters may cast up to their level plus three cantrips per day. This applies to both arcane and divine spell casters. This actually limits the Sorcerer class starting out, but it easly gains the loss back by 3rd level, and exceeds it by almost four fold by 20th level. The rationale for this change includes the fact that Pathfinder rules allow casters to use 0-level spells with no limits to the number of times cast per day. Of course, some 0-level spells (particularly divine spells) have been dropped by Pathfinder such as Cure Minor Wounds.
The Amastasian use of Cantrips does place a limit on these spells, but the increase in caster usage does not seriously over balance their usage. A 20th level Cleric could cast up to 23 Cure Minor Wounds which would heal 23 hit points at most which would range between a single Cure Moderate or Cure Serious Wounds spell. Also, take into account that the caster would have to cast said spell 23 times, taking over two minutes (23 rounds).
There is one minor change to the Dispel Magic between the Dungeons & Dragons 3.5 rules and Pathfinder rules, and that is the cap on spell-caster level bonus to the roll. The Dungeons & Dragons ruls places a limit of +10 so at most a spell-caster's chance to Dispel is 1d20 +10. Pathfinder drops the +10 limit. This change will be incorporated into the Amastasia campaign. The biggest issue is that the DC to overcome the spell is 11 + the spell-caster's level (no limit) so it would be impossible to dispel a magic effect from a 20th (or higher) level caster.
The rules for for Arcane Lock and Knock will be changed, in effect making Knock a specialized version of Dispel Magic. In order to suspend an Arcane Lock with the Knock spell, the caster makes casting check equal to 1d20 +1/caster level. The Diffculting in overcoming the Arcane Lock is equal to 11 + the caster level of the Arcane Lock.
See the Meta-Magic Feats section on the Feats page.