I'm shooting for more lighthearted fare today, villains potentially backstabbing each other, to be exact.
If Darkwing lets it get that far, I think Negaduck's going to regret being so dismissive of Magica's plans. He's downplayed her contributions, mocked her goals, and barely offered enough contrition to keep things from getting ugly. He figures because she's fixated on Scrooge McDuck's #1 dime that she has big-time power, but small-time ambitions. His ego (which is something I'd say he and Darkwing have in common) probably has him thinking he's got her on a string.
She wants the dime because she thinks there are properties to it that will either enhnce her power, or help her accumulate as much wealth as Scrooge. If she's right, that's a little more impressive than Negaduck's goal to conquer a city. If she wound up with that much money, soe could probably buy St. Canard and have it moved to a location of her choice, just to mess with her former ally. Which wouldn't be fun for the inhabitants, but would be fun for how angry it would make Negaduck that he'd been outmaneuvered.