[Rule citation] Same name class ability stacking

[NapazTrix]

I am trying to find the ruling where it states that class abilities with the same name do not stack, if not any effect with the same name does not stack. I have seen plenty of people always says same-name abilities do not stack and have gone by that ruling for so long but I cannot find the written rules for it.

One of my players is asking about multiclassing and stacking "AC Bonus" granted by Monk and Swordsage and insisting they both stack. Without a citation on the rules, I am on the fence about out-right saying no.

[daremetoidareyo]

Those two abilities can't stack. Swordsage ability only works in light armor, monk with no armor

[NapazTrix]

Those two abilities can't stack. Swordsage ability only works in light armor, monk with no armor

You're correct, was misisng that line, or at least it wasn't pointed out to me before.
The question still stands aside from that combination, whether to if same-name abilities stack and the ruling on it.

[HouseRules]

How do you distinguish same name abilities from shard class features other than going into the details?



Gestalt Characters (http://www.d20srd.org/srd/variant/classes/gestaltCharacters.htm)
Class features that two classes share (such as uncanny dodge) accrue at the rate of the faster class.


But it is more along the lines of:
Alternate Classes with the same name cannot be multi-class.

So it becomes a discussion of many things.

Primary Source Rule:
What if they are the same ability but revised?
Are you sure they are different abilities with the same name?

[Zaq]

Moving house and my books are packed, but I seem to recall that it was never spelled out as an ironclad universal rule. Mostly implied by specific examples individually saying that they don’t stack, the most obvious of which being monk and ninja trying to stack those AC bonuses. (And/or abilities saying they DO stack, like different sources of sneak attack.) Which means that RAW is a little murky and that the GM is likely to need to make a ruling based off of perceived RAI (or based off of their desired end result).

How many class features available to multiple classes give a numerical bonus, anyway? I can think of still mind and divine grace, beyond what’s been mentioned, but not many more off the top of my head.