Tattoo Focus
, a Forgotten Realms regional feat, gives +1 DC to specialization school. Does this stack with the +1 from the feat Spell Focus
?
Why?
Yes, they stack.
The reason is because Tattoo Focus (and Spell Focus too, by the way) provides an untyped bonus. Untyped bonuses always stack with each other and with typed bonus, unless explicitly specified.
Stacking
In most cases, modifiers to a given check or roll stack (combine for a cumulative effect) if they come from different sources and have different types (or no type at all), but do not stack if they have the same type or come from the same source (such as the same spell cast twice in succession). If the modifiers to a particular roll do not stack, only the best bonus and worst penalty applies. Dodge bonuses and circumstance bonuses however, do stack with one another unless otherwise specified.