Effect does not stack with DS potions or Call of Rathe. It will stack with DS mage and druid and with sayrn cloak. Cant verify if it stacks with dain ring as I never bothered with that worthless coldain faction.
Does the effect stack with Frostreaver's Blessing from the 10th coldain ring? have been a little disappointed with the number of things that block that effect, mostly regen. But I like the extra attack that the ring effect gives.
No, this effect won't stack with the coldain 8/9/10 ring effects or ranger call of the rathe line of ac/ds spells, either.
If you're farming time, you'll have a chance at the serrated dart, which has the right click savage guard effect which also doesn't stack with the coldain ring. With vengeful and savage guard you'll have superior effects over the dain ring except the ring's regen, but you lose the instant click from the 10th ring so you'll have to decide what's more important.