Conceal Spell [one-action] (Feat 2)
Concentrate, Manipulate, Metamagic, Wizard

Hiding your gestures and incantations within other speech and Movement, you attempt to conceal the fact that you are Casting a Spell. If the next action you use is to Cast a Spell, attempt a Stealth check against one or more observers’ Perception DCs; if the spell has Verbal components, you must also attempt a Deception check against the observers’ Perception DC. If you succeed at your check (or checks) against an observer’s DC, that observer doesn’t notice you’re casting a spell, even though Material, Somatic, and Verbal components are usually noticeable and Spells normally have sensory manifestations that would make spellcasting obvious to those nearby.

This ability hides only the spell’s spellcasting Actions and manifestations, not its Effects, so an observer might still see a ray streak out from you or see you vanish into thin air.