This [Nova] build is designed for any mission in which you will be defending an area. I recommend some sort of external health regeneration for this build, for example, from a companion or a melee weapon mod.(Keep in mind, if you don't have access to an Umbra Forma or some of the primed mods, feel free to use the normal versions of these mods)

Null Star: [Nova] uses this ability for its damage resistance, which is +5% resistance per active star (but only for your health). [Molecular Fission] was added to provide a way to maintain the stars, although if you run out of stars you do have to use the ability again to replenish the charges. Remember that being close to enemies will cause null stars to jump out and deal damage, so decreased ability range makes it easier to maintain your damage resistance.

Dispensary: While Antimatter Drop has its uses, I think it's worth replacing it with Dispensary, which provides a Utility that can help [Nova] and her teammates keep going for longer missions. If your weapons don't adequately deal with crowds of enemies, feel free to keep Antimatter Drop.

Wormhole: While I don't find it necessary to focus on improving this ability, Wormhole can be useful for getting to objectives faster as well as escaping bad situations.

Molecular Prime: This ability is where [Nova] really shines, and what most of this build focuses on. I have added as much ability strength and duration as is feasible, as higher strength slows down your enemies more, and duration will increase the range of the ability. Whenever there is a somewhat large amount of enemies around the objective, You should be using this ability often.

[Nova] is one of the strongest frames in the game, and is extremely powerful during any objective that needs defending. I hope this guide has helped you gain more understanding of her tools.