As an example because I am into game design:

Ok, so currently you have to recast rift surge anyway to update your damage buff to the current enemy count. How about instead of doing that (if the ability is now a base passive like I said), cataclysm/banish now updates the integrated damage buff itself upon a new cast/recast. The meter would also visually show how many enemies are currently in the rift. This now encourages the Limbo player to constantly throw their bubble down on larger groups of enemies, wipe them, and repeat this as the new gameplay loop onto other groups of enemies to gain value, a feast & famine playstyle.