Speed and Skill
This is found in Thaumatology on page 39.
One way to introduce more flexibility into standard spellcasting is to allow casters to exchange extra energy for special benefits. Below are two examples; see Adjustable Spells (this page) for an additional option. All such rules give magic-workers who have lots of spare energy (high personal FP, piles of Powerstones, etc.) a considerable advantage. The GM should avoid them if he wants wizards to be wrinkled old men who value skill above physical conditioning and magical toys.
Faster Casting: Wizards can reduce casting time by one second per 4 extra energy points spent. This option can’t reduce casting time below a second, and isn’t available for ceremonial magic.
Increased Effective Skill: The energy-for-skill tradeoff of Ceremonial Magic (p. B238) applies to all castings: +1 to skill for 20% extra energy, +2 for 40%, +3 for 60%, +4 for 100%, and another +1 per additional 100% of the required energy. Such skill increases affect the roll to cast the spell and the Power of enchanted items, but they don’t reduce casting time, energy cost, or ritual requirements. A further option for Missile spells is to give +1 to the attack roll per extra energy point spent.