User blog comment:Typhron/Flushing Custom Champion ideas/@comment-7709681-20141110233822/@comment-7709681-20141112034140

Actually deals 3% of max. health on each tick, supposing that you putted aside this effect from Vayne's W (Because this DoT True Damage Max. health isn't near as powerful as Kog'Maw once his W is active) she deals her damage, at it's best, every 1.2s, and the DoT requires at least 3s to deal the same amount of damage.

The only thing that keeps it at the same level of this is that is exactly Twitch's innate passive with max. health scale, rather than the flat stackable amount per level. But Lord-y, being an ADC with 15% Armor Pen. from the beginning, along with the DoT, sounds like too much.

And yes, if chasing Frost Shot is the best option, but the penalty isn't as punishing for an effect that can potentially perma-slow the target.