[DF] Not obvious spell - magery enhancement

[Christopher R. Rice]

You want the Easy Casting enhancement from GURPS Thaumatology (p. 28). It's +40% a level and basically lets you treat your spell as five levels higher for the purpose of rituals only (p. B236). You'd probably need at least a level - mostly likely two. Skill 20 requires no gestures and skill 15 needs only a small gesture (maybe something like the Clinton "thumb") and a few words (easily masked as tying into the speech or the like.