Easiest way to fix kaisa

give her a non-damaging passive, up her overall ratios by a small amount, and she's golden.

Hell, you can go with her theme and make her passive a feeding-the-voidling sort of passive. The more she kills, the more it consumes, and attacking uses its energy. Make the damage based on that condition.

No reason that with her entire kit that she needs to be dealing 20% of my missing hp every 2 auto attacks. There's no mechanic to it, it's just a free obscene auto attack enhancer. Kog'maw has that as one of his abilities and he cant dash around go stealth or do loads of targeted damage.