Perhaps give it treatment similar to AST's Collective Unconscious. By this I mean whilst the DNC is using Improv everyone gets the benefits of both things as they do now, however if they move after using it then everyone that was in range gets to keep the 10% increased healing for whatever duration of time.

I find the animation of it a little underwhelming though. All that arm flaying just feels like you are RPing an inflatable arm waving tube man...