User blog comment:FelisaeNoctus/Shadowcat, the Familiar/@comment-4652200-20130409105018/@comment-7972240-20130409110424

The passive does need a bit of work, yes, but the concept is intended more for spiking. Her base damages are rather low to begin with, but if you rapidly fire of Qs in succession, say, you just dumped a hell of a lot of damage on someone's head in a short period of time. Even more if you popped your ult out as well, as the Lich mirrors a percentage of the damage you're dealing with his own spells. While at first glance it may not seem like it's worth much, it's surprisingly powerful when the numbers are worked out.

I may do some more tweaking with her overall numbers in order to give the passive more of an impact, but it's a tricky balance due to how quickly she can go from background support to face-melting assassin.