So interesting idea came up when talking to a friend about megavolt. Inventor themed metamagic. Variable action megavolt. And a 5e warlock casting system for megavolt.
Metamagic
This idea was straight forward. 'Widen spell' on megavolt. This would also encourage the design space of spells as unstable actions and therefore 'metamagic' on those unstable actions.
Variable Action
I REALLY like this idea. Imagine using megavolt one action for a shocking grasp like effect. Two actions for a lightning bolt effect and three actions for a chain lightning effect. Or a simpler example, explosive leap could offer more distance per action used.
5e Warlock style casting
Imagine if your innovation could handle a limited number of unstable actions (equal to your int mod or something, if it were up to me I would use this limit to replace the flat roll.) before requiring some out of combat repair time (10 min or 1 hr or something). This sort of mimics the 5e warlock regaining spell slots on a short rest.
These are admittedly not fully fleshed out ideas but what do people think?