Ability Strength mods affect the damage of Null Star, the base damage of Antimatter Drop and the slowing effect and explosion damage of Molecular Prime. One interesting fact about Molecular Prime is that negative Ability Strength will speed up enemies instead of slowing them down. Ability Range mods affect the attack radius of Null Star, the range of Worm Hole and the explosion radius of Molecular Prime. Ability Duration mods affect the number of particles of Null Star, the duration of Worm Hole, the wave expansion duration of Molecular Prime and the duration of its priming effects on enemies.
So, all things considered, here are some builds you may want to try on your Nova: