Originally Posted by Axzarious
Another idea on top of that- a variant of Wriggles lanturn that instead had a chance to deal bonus damage upon spell casting instead of auto attacks.
Though I think the chief concern here is that if these were implimented, the spirit stones might become a very tempting option for laners.
Wriggle's is a bit depressing to purchase now, I would like to see an upgrade option for it. I imagine the primary reason it doesn't have one is that both life steal and armor on physical damage dealers can get extremely desirable incredibly fast. Wriggle's wasn't a bad buy by any stretch on most lanners in Season 2, I imagine the spirit stones won't be in season 3.
As for a chance on spell casts - that's generally a bad idea. Abilities have an incredible range of cooldown times, so applying something like Wriggle's passive on ability casts would mean Skarner and Evelynn would see their clear times become unusually impressive - while champions with longer cooldowns on anything capable of procing it (Such as Master Yi and Gangplank) would pretty much never buy it because of the vast difference in effectivenss it has on them compared to Evelynn and Skarner.
With abilities the only feasible effects generally have to boost things by a percentage (like 10% increased damage) so that cooldowns don't matter. That, or include cooldown times in the formula for chance and bonus damage - which could become complicated to represent in a tooltip.