Thoughts on how to buff Evelynn
Disclaimer: This is a list of how I would like her abilities could be improved, I am not stating that she needs to have all of these changes.
Hate Spikes:
Her auto attacks and Ravage apply stacks of a 'Spite' debuff. Only one enemy can have this debuff at a time, so attacking another unit removes all stacks from the previous subject. The enemy with this debuff is prioritized by Hate Spikes (basically unchanged from current behavior, but adds clarity on what is being targeted) and Hate Spikes deals increased damage based on the number of stacks.
Makes the attack speed boost from Ravage more useful even if you have not built significant AD or on hit effects, resulting in a more consistent kit.
Dark Frenzy:
Damage over Time effects will not reapply any associated slows unless they are refreshed first. Now they do not instantly negate the slow removal, unless you are standing in an AoE that reapplies the DoT.
Ravage:
35 / 55 / 75 / 95 / 115 (+ 50% AP) (+ 50% bonus AD) Physical Damage per hit -> 35 / 55 / 75 / 95 / 115 (+ 50% bonus AD) Physical Damage and (+ 50% AP) Magic Damage per hit
If you have enough AD to seriously can about armour penetration, you do not have enough AP for this to really matter. If you have enough AP to care about magic penetration, you really care about your abilities doing magic damage. And yes there are abilities in the game (or at least Fizz's Urchin Strike does) that do both damage types.
Also after the change to have it apply on hit effects, it now does not apply spell vamp or life steal which is very strange. That should be looked at.
Agony's Embrace:
Reduced shield per champion hit, but get additional shield and duration on getting kill(s) or assist(s) before the duration expires. Synergies with the reset on Dark Frenzy to allow you to get out or continue fighting if you manage to take someone down. If you get a kill or assist within 6 seconds of casting, the net amount of shield should be greater that current for the number of enemies hit initially in all cases assuming at least 5 champions per team.
Situational buff / nerf. Adds more gameplay to it than just landing a near instant AoE.