Arcane Armor Mastery... wait, what?

[Douglas Muir 406]

Arcane Armor Training: reduces spell failure chance for wearing armor by 10%, allowing the caster to wear various light armors. Okay, that's fine.

Arcane Armor Mastery: next feat up the chain, requires AA Training above and caster level 7th. Reduces spell failure chance by 20%. About half the medium armors have 20% failure. Chain mail, though, has 25%. So if you take this feat and you want to wear chain mail, you'll have to eat that 5%.

Except... mithril chain mail is equal to or better than ordinary chain mail in every way. And it has a 10% failure. And while it's a bit more expensive (1,100 vs. 200), by the time you're 7th caster level this is pretty meaningless.

So: why would you ever ever ever take AA Mastery, when you could just stop with AA training, buy mithril armor, and save a feat? Put another way, doesn't the existence of mithril chain make this feat almost completely pointless?

Doug M.

[nate lange]

mithril breastplate has a 15% ASF, so 0% with AAM! mithril fullplate only has 25% ASF- so with AAM you'd only have 5% ASF to worry about...
so, you'd take it if you want to wear heavier armor (especially for multiclassed melee/casters and eldritch knights)

[Ishpumalibu]

I don't like either of the feats anyway since I have to use a swift action.

[Artanthos]

And this feat allows a hellknight signifier to cast in hellknight plate without spell failure.

[drumlord]

Mithril shirt is a mithral chain shirt, not mithral chainmail.

Mithril shirt: AC +4, 10% failure, 1,100 gp
Mithril chainmail: AC+6, 20% failure, 4,150 gp

So arcane armor training is just enough for mithril shirt with no chance of failure. Arcane armor mastery is just enough for mithril chainmail with no chance of failure.

[Douglas Muir 406]

Ah! Okay, I understand better now. Many thanks!

Doug M.