You inundate the area with strange energies from the Plane of Shadow, warping the effects of magic.

A flood of mystical shadow-power renders casting more difficult. To cast most spells while in, or into, an area affected by flood of shadow, the caster must succeed on a Spellcraft check (DC 15 + spell level), or the spell is lost with no effect.

Mysteries or any spells of the shadow subschool can be cast within or into the affected area without making the Spellcraft check. In addition, if a mystery or a spell of the shadow subschool originates in an area affected by flood of shadow, its variable numerical effects are increased by 50% (as if it was empowered), although its level does not increase.