Nova is very powerful.
Seriously, it's on the level of some of the better shards.
To not use it is complete sacrilage.
The trick to rainbows, especially rushes, is to diversify your quanta useage as much as possible and use as many elements as possible, so then your novas a more powerful.
Lycans are good, grabboids are good, deflags are good. Fog is okay (I would personally prefer the normal shield or a tower shield) Sanctuary makes little sense if you're trying to outrush, lightning makes little sense if you're trying to outrush, mummies are too expensive.
Replace 6 pillars with novas, change the mark to earth. Replace some things for cheap hitters. Firefly, forest spirit, poison, graviton fire eater and horned frog aren't terrible ideas. You can use precognition if you want to thin your deck out.