I know there's quite a few variations of Nebula decks out there already, but this is what I've been playing after lots of tweaks. After playing this a LOT since Nebula first showed up (I've been super excited about her), I can say that this deck is all about clogging/restricting 2 lanes before turn 6, so you see a lot of people retreat which makes it important to know when to snap on turn 3 or 4. So, this deck hasn't been a huge cube winner, but it has been a consistent winner of 2 cubes with shorter games lol..
Card choices that you might find odd:
No Armor?: I did struggle with this choice, but ultimately I found myself able to use Prof X to protect Nebula. I don't always put her down immediately so I don't give away my game plan too early
Rescue: Goes well with Prof X in succession, plus hopefully Nebula with them is usually a won lane, and you can end using Sentry for 10 power with Jeff in Prof X lane if needed
Sentry: I've been itching to use this guy since I got lucky and pulled him from CL track lol.. if you're able to fill the right lane or Prof X it, having Sentry plus Demon or even Jeff is a nice bit of power to throw down in a lane without having to worry about Void. And yes, very rarely you get that awesome Sentry/Viper combo off, but it's best not to expect it.
Thanks for checking this out, any suggestions/questions are more than welcome in the comments!