I'm learning Evelynn this week and I'm noticing some discrepancies in the mobafire builds between getting attack damage and ability power.

Should I focus on one or the other or just get items that have both?

Also I'm wondering how important life leach is to Evelynn? It would seem since a significant portion of her damage is supposed to come from basic attacks that you would want some to help survive in specific situations or is it better to just build defensively instead if you're worried about survival?