User blog comment:Atmey/Acidex/@comment-6102571-20130210220701/@comment-3529242-20130211085654

His AS and it's scaling are lower than average, even lower than Thresh, lvl 18 without any AS items he has 0.776, he barely can break the 1 mark.

The 3600 damage you suggested, lets count how much time does he have to attack to reach that. Assuming he got 2 PD his AS would be 1.38, I am lazy so I will just multiply AS with damage.

DoT increase rate= 20*1.38 = 27

Time to reach max stacks= 15/1.38 = 10.8 seconds

Average damage during stack building = 20*7.5 = 150

Total damage in the first 10 seconds, = 150*10 = 1500 magic damage.

1500 to a single target in 10, and assuming you can survive 10 seconds with 2PD, anyone can best that, a carry or a bruiser with 2PD would deal at least 10 times the damage. It is not OP at all, just slightly stronger version of TW or GP's passives.

First I thought I'd put the stacks to be unlimited but I think his W might be abused this way.