dcollins said:
The additional strange thing about the FAQ ruling is the existence of the core item called the caster's shield, a shield with a spell on the back "as on a scroll". One of the specific rules written for it is that "the user can cast the spell inscribed on the back of the shield with no chance of arcane spell failure due to the shield" (DMG p. 183).
The implication would seem to be that normally shields do contribute arcane spell failure when reading scrolls; it seems like that's an advantage that disappears from the item with the given FAQ ruling on scrolls-in-armor.
Nice catch!
My take on it:
1) Spell Completion Items provoke AoOs just like spells.
2) Spell Completion Items force the user to "perform the short, simple, finishing parts of the spell casting (the final gestures, words, and so on)".
I do not hear anyone claiming that you can use a scroll in a Silence spell area. The word "words" here means speaking not reading since you do not read when casting normal spells. Since the word "words" means speaking or verbal component, the word "gestures" must mean somatic.
The only component not mentioned at all (in this section) is material.
And the phrase "perform the short, simple, finishing parts of the spell casting" quite clearly states that you are casting a spell.
3) "The preparation is done for the caster, so no preparation time is needed beforehand as with normal spell casting." This seems fairly clear. No studying beforehand as with normal spells.
4) "Activating a scroll requires reading the spell from the scroll. The character must be able to see and read the writing on the scroll." "Deciphering a scroll to determine its contents does not activate its magic unless it is a specially prepared cursed scroll."
These two sentences together reinforce that just reading the scroll silently does not activate it. You must read it out loud.
5) dcollins' find of the Caster's Shield reinforces that somatic components are required for scrolls since the Caster's Shield allows casting of a scribed spell "with no chance of arcane spell failure due to the shield".
6) Spell Trigger items explicitly call out that they are simpler than Spell Completion items and do not require gestures, merely speaking a single word. Again, the use of the word gestures when discussing spell completion items implies Somatic component.
7) The definition of Spell Preparation in the PHB explicitly calls out that most of the preparation (just like with a scroll) is done ahead of time (i.e. during study) and that the caster merely "finishes the casting with the appropriate spell components - a few special words, some complex gestures, a specific item, or a combination of the three".
This is virtually identical to the description of casting a spell from a Spell Completion item (both in the DMG and in the PHB glossary) with the exception that it includes the possible material component which is explicitly dropped for scrolls (in several places in the books due to it being used up during scroll creation).
Taking any one of these bits of information is not overly compelling in and of itself, but looking at them all together is much more compelling than the no somatic side of the fence. So, based on what little information is in the DMG and PHB, using a scroll is the same as casting a spell except no material components and no studying ahead of time.
Verbal and Somatic components are part of casting the spell from the scroll.
The power of the scroll (i.e. DC of any spell) is determined by the preparation (i.e. creation) process, not the caster using it.
