Originally Posted by
TheRez
When you or the linked target gains a critical periodic damage or healing effect, the other gains increased periodic damage and healing lasting for 7 sec. You gain 3%, while the target gains 1%. Stacks up to 3 times. Dark Intent lasts for 30 min.
This means that when you have a periodic critical strike, you gain 3% increased periodic damage and he gains 1%, stacks up 3 times you get 9% and he gets 3%. Now, if the warlock gets a periodic crit effect, the effect is reversed and he gains more benefit from it than you. It there is a range it shouldn't be more than 30 or 40 yards, which you should be standing relatively around the ranged DPS anyways.