ability percentage stacks?

[Gemina]

That would make sense, do you have data or a link to something to show this?

No data or link is needed to validate it. It is simply using the formula provided in the descriptions by both abilities.

[Vulcwen]

No data or link is needed to validate it. It is simply using the formula provided in the descriptions by both abilities.

Eh.. that's not an argument. Tooltips can be wrong, and have been in the past, besides they provide no information about how they combine.
It's a generally accepted theory that it's multiplicative, and I have tested it a bit a few months ago. I can't find a recent source with test data however, so I have no valid proof ready. I might get back to this later, to show some data :P

[Gemina]

Eh.. that's not an argument. Tooltips can be wrong, and have been in the past, besides they provide no information about how they combine.
It's a generally accepted theory that it's multiplicative, and I have tested it a bit a few months ago. I can't find a recent source with test data however, so I have no valid proof ready. I might get back to this later, to show some data :P

I wasn't arguing. I was just backing you up But I was under a previous impression that tooltips are accurate to what they say. I never tested it myself to see if it is doing what it says it does. Though, I guess technically if we went strictly off the tooltip, I think the formula would be ((.05 + .4) / 100%) = 45%

I also assume that healing buff stacks are multiplicative because HP restoration isn't a set number, but we would have to see the actual coding that goes into HP restoration along with the RNG constants that influence them. At least I think anyway. I'm not the best at this kind of thing.