A Casual Guide to Nova

I have now played Nova to level 10, giving me credentials as a casual Nova player. As many Nova players have suggested and data support, Nova is best played in Quick Match or lesser venues. A team dedicated to supporting Nova could leverage her abilities, but for most pick-up games, results with Nova will be feast or famine, denying her a favorable place in ranked play. For casual players, Nova is a great choice given her stealth and both basic and heroic abilities that are easy to use.

This mini-guide will serve to address how best to play this character and how best to maximize Nova if she is a member of your team.

Assumed Talent Tree (option1/option2/option3):

Ambush Snipe , Gathering Power, Anti-armor Shells, Precision Strike/Triple Tap, Lethal Decoy/Double Decoy, Crippling Shot, Bolt of the Storm/Precision Barrage/Fast Reload

How to play:
Early: Until level 10, Nova should attack minions for XP and try not to get killed. If enemies are aggressive, consider positioning to catch retreating Heroes with less than 1/2 health. Don't try to ambush and burst down enemies at this phase unless they have overextended themselves in a lane. Holo Decoy can be used to deplete ammo from Towers throughout the game. If the early game environment is hostile to laning (5-man roving enemy team), distraction of Heroes and ammo depletion with Holo Decoy are reasonable activities.

Middle: Once you obtain either Triple Tap or Precision Strike, you are ready to burst down light to moderately armored Heroes. Rotations: Holo Decoy>Pinning>Snipe>Heroic Ability. This rotation (ideally) depletes a few cooldown abilities (Holo Decoy), slows the target for easier Snipe and Autoattacks and gets kills with either Heroic ability. If you cannot accomplish Pinning Shot and Snipe in <1sec you lose the benefit of Ambush Snipe favoring the more conservative: Holo Decoy>Snipe>Pinning>Heroic Ability.

Late: Nova can begin to burst kill all but the most resistant Heroes after taking Crippling Shot, though non-Warrior characters will remain the best targets. If you took Triple Tap, position yourself to catch retreating heroes and don't use unless a kill is assured and especially not near structures or groups of enemy minions or mercenaries. If you took Precision Strike wait for double/triple/quad/mega kill opportunities.

Tactical use of Abilities:
Snipe: A skill shot with long range. Used mostly for burst damage. If you took Psi-op Rangefinder, can also be used in fights that persist to catch runners.

Pinning Shot: Damages and slows enemies early and increases damage with Crippling Shot. Good for preventing escapes, rarely good for preventing pursuit.

Decoy: A double of Nova that appears to attack enemies. Good for tricking enemies into using cooldown abilities, breaking stealth/concealment and for augmenting damage in late game. Occasionally can be used to kill a retreating Hero given its relative long range.

Stealth: Nova's stealth ability is what makes her a good casual-players hero. Stealth allows you to engage at the time and place of your choosing. Don't squander stealth by bad positioning, entering fights you cannot possibly assist meaningfully or win. Don't think too highly of stealth. Some players are very good at spotting stealthed heroes. Stick to bushes/vents when possible, advance along borders instead of in the open and shadow other players if no other cover is available.

Ineffective Pursuits:
Taking Mercenary Camps alone, laning alone, holding objectives or attacking structures.

How to play with Nova:
Don't ask or expect Nova to engage in 'Ineffective Pursuits' as above. Do watch where Nova is positioned. Feeding Nova with grabbing abilities helps keep her out of harms way. Ideally, grab an already damaged character (3/4 health) as Nova can usually burst most non-Warrior characters at this level of health without use of a heroic cooldown.

Summary: 
Nova is a fun hero. Strive to lead your group in either kills or hero damage or both and don't get caught unstealthed and out of position.