For a while, there were two primary artifacts for champions looking to stack the most Will: Deadshot's Visor and Abin Sur's Lantern.
You picked one or the other based on the damage stat you preferred. This created awkward tensions where being a better controller necessarily lead you to deal more damage. We've remade Abin Sur's Lantern to make it the premier artifact for building lots and lots of Will by taking off any damage that would bias it for or against specific Controllers.
At the same time, we took a hard look at the Will Battery keyword. While we liked how it encouraged Controllers toward cooldown reduction, in practice its suitability depended far more on whether a champion's kit had a low cost, spammable skill. We opted to replace this keyword with new one: Will Collector, which follows an established pattern which has already been shown to layer well on our coin mechanic.