This spell makes it difficult for the subject to cast arcane spells, use spell-like abilities, and use some abilities granted by arcane spellcasting classes. The subject must succeed at a concentration check (DC = 10 + 1/2 its caster level) in order to cast an arcane spell, use any spell-like ability (even those that come from a divine source), use arcane spell completion or spell trigger magic items, or use any of the following class features that come from an arcane spellcasting class: arcane school powers, arcanist exploits, bardic performances, magus arcana, or witch hexes. Spells, spelllike abilities, or class features that take a free, swift, or immediate action aren’t affected by this spell, nor are mythic spells or mythic powers. While under the effect of this spell, if the subject must attempt a concentration check to cast an arcane spell or use an arcane spell-like ability for any reason other than the effect of this spell (such as casting defensively, being injured while casting, and so on), it takes a penalty on that check equal to 1/2 its caster level.