Does anyone know what an attack speed bonus being skill based instead of item based means?
I-IAS is converted to E-IAS using the formula
EIAS = [(120 * IAS) / (120 + IAS)]
So having 100% I-IAS results in 54% E-IAS, 200% -> 75%, 300% -> 85%, etc
EIAS from items, skills, auras, slows, etc is all added together, and the total % EIAS is capped at [-85, +75]
So no attack animation is ever slowed more than 6.667x slower, or speed up to 0.5714x the base speed. And for non-player actors / minions there is always an additional 15 frame delay between attacks, regardless of %eias
since you can't stack above +75% EIAS, the total bonuses of %EIAS provided by demonic mastery & engorge can put you near the max attack speed for minions
Supposedly summon tainted already have some +% eias provided by the skill which was never displayed until this yet-unreleased patch, mastery goes up to 25%, engorge goes up to ~35%
So you should presumably hit the 75% max speed on them without any other sources like fanaticism, which means fanaticism would have no impact on them anyway
And they'd be attacking at 22 FPA (7 frame animation + 15 frame delay)