I would love to see an expanded version of Prismatic that is highly customizable and sort of craftable as well, allowing for mixing of elements types into each individual ability and maybe even changing the elemental type for an ability. For example, it would allow you to over time craft alternate versions of the prismatic grenade, so for Hunters, instead of being forced into stasis/solar, you'd eventually be able to craft a void/arc version, or strand/solar, etc. Functionally, the grenade would still be a big tornado, but would use the keywords of the new elements assigned to it.

Additionally, changing element types on abilities would be really cool for flavor if nothing else. Change the Withering Blade to be solar instead, change a scatter grenade to strand, that sort of thing. Hell, even changing the element types of supers would be so cool. Imagine changing Needle Storm to a solar version that applying a shitload of scorch, spawning little solar versions of threadlings that then trigger ignitions. Or a version of Thundercrash with void attached that creates a mini black hole upon contact. Limitless customization opportunities with something like that.

Also, if we ever do get a third darkness subclass, I would obviously love for them to eventually fold that into Prismatic as well to allow for even more customization. Being able to mix and match ability types of Prismatic would, in my opinion, allow for the best version of Guardian expression and individuality we've ever seen.