Are boosts additive or multiplicative with other bonuses?

[Saucy Jack]

Let’s say I have +10% attack for whatever reason. If I boost attack by 1%, does that mean my total boost is (10+1) = 11%, or does it mean my total boost is (10*1.01) = 10.1%?

[Elgareth]

You can hover over your stats to see all the bonuses you get and what the result is.
They seem to be additive, getting a new source of a 1% bonus gives you 1% more straight up.
I probably have too small percentages to test with where it makes no difference for my numbers, archmag is probably right.

[archmag]

They are multiplicative. +10% and +50% will result in total of +65%, not 60%.

[Serpentarius]

It depends on the bonus type. if a bonus does not show a % its additive to your base value, if it shows a % its multiplicative with CURRENT value.

[Maticolotto]

Any bonus shown as % in the game is multiplicative with each other and with itself. If you have two Essence Catalysts and they increase Channeling Efficiency by 20% each, your total bonus will be +44%.

Bonuses shown as a plain absolute number are additive with each other and with itself.

[HumbleImp]

Originally posted by archmag:

They are multiplicative. +10% and +50% will result in total of +65%, not 60%.

I think if your talking attack speed and going towards 0, multiplicative works against the total though so 10 + 50 percent would be 55 not 65.

[archmag]

If you are talking about reducing periods between attacks or reducing spell cooldowns, it will be displayed as -10% and -50% and not with "+", which means resulting cooldown will be (1-0.1)*(1-0.5)=0.45. Or -55%, exactly as you said.

But it they are penalties, +10% and +50%, the resulting penalty will be 65%.

The rule is the same in both cases: (1+x)*(1+y)-1.

[Saucy Jack]

So does that mean it's not worth it to try and boost attack speed as much as I can? Was toying with the idea of a "machine gun" build.

[HumbleImp]

Nah, That was definitely useful to do at certain points.

[Serpentarius]

Originally posted by Saucy Jack:

So does that mean it's not worth it to try and boost attack speed as much as I can? Was toying with the idea of a "machine gun" build.

Machinegun builds can be useful, but in diffrence from Magic Research 1 there is a hard cap of 0.01 attack delay so you can't just annihilate the enemy by having no attack delay at all. Also in order to reach such speeds you need extremely high level and it comes at the cost of damage or survivability.