Type: General
Source: Complete Scoundrel
Your arcane studies allow you to mingle arcane magic of different flavors for great effect.
Prerequisite: Ability to cast 2nd-level arcane spells, steal spell.
Benefit: Your spellthief levels stack with levels of other arcane spellcaster classes (that is, levels of any class that grants arcane spellcasting other than the spellthief) for the purpose of determining what level of spell you can steal. For example, a 4th-level spellthief/4th-level wizard could steal spells of up to 4th level, as if he were an 8th-level spellthief.
Your spellthief and arcane spellcaster levels also stack when determining your caster level for all arcane spells. The character described above would have a caster level of 8th for both his spellthief spells and his wizard spells.
In addition, you do not incur a chance of arcane spell failure for arcane spells cast or stolen from other classes, but only if you are wearing light armor. You incur the normal arcane spell failure chance when wearing medium or heavy armor or when using a shield.
Special: A spellthief does not incur a chance of arcane spell failure when casting spellthief spells in light armor. He incurs the normal arcane spell failure chance for other arcane spells he casts, including those stolen from arcane casters.