My Witchdoctor got a new power last night, Widow's Touch, that says it slows an enemy for 5 rounds. When I use it the yellow "Slowed" note over the target's head flashes three times, as if the effect were activating three times in a row on a single casting.
At the end of that enemy's turn the same round there was a purple "Slowed" over his head as if the effect had already worn off. When I put my mouse over that enemy on the battleboard as the next round began, it showed he still had "Slowed 4" and "Slowed 2".
So it looks like Widow's touch puts a total of 3 Slowed's on the target at the same time - one for 5 rounds as it should (Slowed 4 after the enemy's 1st turn under the spell), another for 3 rounds (Slowed 2) and a third one for only a single round that wore off as soon as he moved.
I don't know what exact effect Slowed has - I'd assume it reduces movement range but I don't know by how much. Does stacking multiple Slowed effects like that indicate that it slows them down more at first then the effect wears off gradually - for instance a -3 to movement at first, then -2 a couple of rounds, then -1 for the last 2 rounds? Was that the intent? (Pretty cool effect if that's what it actually does.) Or are the multiple effects just a total bug?