For my own games magic requires 2 of the following elements: incantation, gestures, and materia.
Incantation consists of arcane mutterings, power words, true names, etc. These are usually in ancient and often dead tongues. Requires the caster be able to speak and enunciate clearly. If the caster suffers damage to the mouth a DRM +1 applies. If rendered deaf casting a spell with an Incantation equates to a +2 DRM.
Gestures are the somatic movements requires to conjure and bind the magic to the caster's will. The caster must be free to move and have at least one hand free. Being grappled, entangled, under water, etc. carries with it at least a DRM of +1 possibly +2.
Materia are the components such as eye of newt, footfall of a cat, a blessed piece of leather consumed when the spell is cast. Materia are generally cheap and easily replenished between adventures, a caster with Materia spells must purchase a component pouch between adventures costing 25 coins and weighting 1/2 ENC.
Every spell used by an adept (I prefer this word) has to have 2 of the three for every spell. If at the time the spell is attempted an element is impossible or unavailable, the caster suffers a DRM of 2 or a whole die if both are impossible.