Dark Harvest scales horribly, and is only strong because of the resets

The resets though are what make it strong on AoE mages, who didn't really have a keystone previously.

So, what if the resets started out weak but the harvested souls improved them?

For example:

• at 0 souls, Dark Harvest procs after the first one (gained through a reset) could do 0 damage (but still harvest the soul)
• at 10 souls, they could do a % of the first proc's damage
• etc

This should nerf it early/midgame specifically for those champions who can easily reset it, while keeping its core idea of scaling with usage.