How do cooldowns stack?

[Vrimmel]

I'm working on LK hm and I'm wondering if it's possible to stack cooldowns from different players (and myself, AD+DP) and if so how do they stack. Are they additive or multiplicative?

Spells related:
Divine Protection
Ardent Defender
Safeguard+Intervene
Divine Guardian
Hand of Sacrifice
Pain suppression

Edit:
Also wondering about vigilance.

[Meloree]

I'm working on LK hm and I'm wondering if it's possible to stack cooldowns from different players (and myself, AD+DP) and if so how do they stack. Are they additive or multiplicative?

Spells related:
Divine Protection
Ardent Defender
Safeguard+Intervene
Divine Guardian
Hand of Sacrifice
Pain suppression

Edit:
Also wondering about vigilance.

Multiplicative stacking. IE: AD+DP is 36% damage reduction.