Fast Cast Spontaneous Spell
From Project: Redcap
Magi can Fast-Cast spells in response to an attack or other emergency. For example, a magus could fast-cast a spell to parry aside an enemy's sword, to to block a hostile spell, or to save himself from falling off a bridge.
Whenever a magus comes under attack or is suddenly endangered, he can try to defend himself by fast-casting. Success is not guaranteed; first, the magus needs to react in time, and then needs to cast an appropriate spell of high enough level.
What Spells can be Fast-Cast
Fast Casting and Initiative
You do not need to roll Initiative to fast-cast a spell. You can fast-cast at any time, usually in response to something bad happening like getting attacked or having a spell cast at you. You can do this even at the start of battle before your first turn has come up yet. If you fast-cast, that's basically a free action and it does not stop you taking another action, even casting another spell, that combat round.
Fast-Casting Speed Roll
Although you can attempt a fast-cast spell at any time, you aren't always fast enough to actually defend against the attack. That's what the fast-casting speed roll is for (ArM5, page 83): to determine if you fast-cast the spell in time for it to do any good. As noted on p. 83, if you fail the speed roll, you can choose to abort the spell, which is probably a good idea because there is no point in risking fatigue loss or a botch if it's too late for your spell to protect you.
Note that the rules say that if the Fast-Casting Speed roll fails, "the maga can cast no further spells in that combat round". The general rules for casting spells in combat, on the other hand, say that it takes about a round to cast a non-fast-cast spell, and that thus "a magus cannot cast more than one normal spell, or a fast-cast and a normal spell, in the same round".
A lenient reading of these rules is that fast-casting is essentially a free action, as noted above, so that in a single round you can cast a normal spell and, if you wish, also fast-cast one or more spells. This reads the first quote as "the maga can cast no further fast-cast spells in that combat round".
A more stringent reading is to maintain that since casting a normal spell takes an entire round, "a magus cannot cast (more than one normal spell), or (a fast-cast and a normal spell), in the same round". On this reading the magus can usually cast no more than one spell per round, be it a fast-cast or a normal spell; exceptionally fast casters may be able to fast-cast several spells in a single round, but no magus can cast a fast-cast and a normal spell in a round.
Casting Total and Level
Fast-Casting is always done with a firm voice and bold gestures. The caster gets the normal bonuses for these Words and Gestures (ArM5, page 83). There is an additional penalty to the Casting Total due to fast-casting, and fast-cast spells incur extra botch dice (ArM5, page 83).
Against physical attacks, the Fast-Cast spell must meet the normal level needed to stop that attack, according to the Spell Guidelines. For example, to deflect a single blow from a wooden weapon using a fast-cast Rego Herbam spell, the magus would need to duplicate the effects of Repel the Wooden Shafts (ArM5, page 138), at the same Spell Level.
Against spells, a Fast-Cast defensive spell of one-half the level of the incoming spell is usually sufficient to defend against it, although the attacking spell still succeeds and has effects. The Storyguide should use his or her best judgment as to whether a given Fast-Cast defensive spell will be effective, and whether its level needs to be slightly above or below this rule of thumb.
- Ars Magica Fifth Edition, Chapter Seven: Hermetic Magic, "Spellcasting Options - Spontaneous Spells - Fast Casting", p. 83
- Ars Magica Fifth Edition, Chapter Seven: Hermetic Magic, "Spellcasting Options", "Words & Gestures" Insert, p. 83
The history of this page before August 6, 2010 is archived at Legacy:fast_cast_spontaneous_spell