do buffs stack?

[KoroushSensei]

if i use foresight, shadowskin, shadow wall are they stacking on each other?

[aerolol]

Yes they are.

[Urthdigger]

The only case I've ever seen of buffs not stacking is a debuff that marauders and ninjas can apply to make mobs take 10% more slashing damage, and scholars cannot have Shadow Flare and Sacred Soil up. Outside of those though, most every buff can stack.

[elemental10]

In case of your situation:

Foresight increases defense, while Shadowskin and Shadow wall increases mitigation.

Foresight will stack with either Shadowskin OR Shadow Wall.

Shadowskin and Shadow Wall, however, stacks multiplicatively.

If you're up with Shadowskin and Shadow Wall, a damage of 1000, will go through Shadowskin first. Shadowskin has a 20% mitigation, meaning the damage will now be at 800. Then, it will go through Shadow Wall which has 30% mitigation, therefore the damage will now be at 560 = 800 * 70%.

As you can see, if done additively, both Shadow Skin and Shadow wall would mitigate 50% of damage but multiplicatively, only mitigate 44%. Therefore, it is recommended to use one after another, instead of stacking it up.

Foresight increase defense and how much mitigation you get per point of defense is a whole lot of another story, but it's decidedly doesn't scale very well and foresight only nets you a mitigation around +3% or so.