My gut instinct is that scaling anything to EDR is a bad idea, mostly because of the ludicrous bonuses given by weapon skills. There's no way to scale that damage in a way that's useful for most characters and not hideously broken for someone dual-weilding axes.
Exactly - but if you scaled it low enough that +40 EDR doesn't break it in half, then it won't scale aggressively enough for anyone who's not using that specific strategy. I mean, I would think so. The average character is going to get, what, 20 EDR? And then you can triple that with the first skill of one skill tree and the last skill of another. I'm pretty sure there's no way to make it work for both extremes.
I think the answer there is to use for the portion of the damage that needs the least scaling - . Few monsters resist it, and those that do are mainly late in the game. Use no base damage for it, and only a modest scalar. It'll never be the bulk of what you're doing with the effect, but it will allow a little more to get past and for the -heavy build. Put the bulk of the damage on and . I'll agree that generally is dangerous for scaling because it varies so much from character to character, but this is eye-lasers we're talking about. Any character that's maxed out a weapon skills for the bonus probably wants to get in close and smash face in melee. generating a subset of the damage on a single-target ranged attack on a timer is probably not an issue. If it were a spammable effect or the sole scaling of the lasers, that'd be another thing entirely, but if broken up as mentioned above, it's probably harmless.
You know it just hit me earlier today that the best way to buff Third Sight would be to make it something that triggers automatically; say a 5% chance of triggering whenever you're hit and whenever you cast a spell.