After the recent changes on nova i find that the build around "lethal decoy" is the safest way to go and the one with highest overall damage potential.
The patch has taken away the burst potential of nova. But combining "Rapid Projection", "One in the Chamber" and "Lethal Decoy" you can spam your E every few seconds and get a good amount of damage out of it.
This said this build is intended to play nova as a poke hero.

This is my first guide here and if it helps somebody it will be worth my while.

I choose "Rapid Projection" over "Holo Stability" for a couple of simple reasons:
-First is damage output, the decoy is very fragile and is unlikely that "Holo Stability" will deal all the damage it is supposed to. For this reason "Rapid Projection" will prove a better choice, given that it will have time enough to dish out all of his abilities and auto attacks before banishing/dying.

-Another important point is that the fights are most of the time in movement, "Rapid Projection" allows you to place your decoy where its needed more often.

-With a low CD on the clone you can use it to block projectiles... got problems with Li Ming? Intercept her abilities with your clone and see her running.

-The first talent choice gives you more range on your pinning shot and works perfectly with "One in the Chamber" providing you with a good poke from a safe distance.
The other choices on this bracket aren't as good.

-The second choice would be "Rapid Projection", for the reasons stated above.

-"Anti-armor Shell" does not provide an upgrade to your damage nor your clone's damage.
"Snipe Master" is very unreliable and should be avoided. If you pick this talent you will find yourself walking out of position in order to get a clean snipe and sometimes dying in the process.

-"Precision Strike" strike over "Triple tap" in most cases given it provides a "zoning" potential persuading enemies to chase you and has an useful global range for an example.

-For the best single target poke "Double tab" proves the winner in this bracket. It provides you with a second slow and some damage from a good distance (ability damage followed by a +80% AA).
With this talent, your clone (at level 20) dishes out 1000 damage to a single target.

-"Lethal Decoy", sole reason for this guide...

-For level 20 the to go choice will be "Rewind". With this talent you can double your poke capabilities when needed.
You need to burst down some target? Pop your clone, your abilities (always followed by an AA to take profit from "One in the chamber"), use "Rewind" and repeat.

If for some reason you need some AoE, the map "Infernal Shrines" is an example where some AoE could come in handy. These would be the talents you need to switch:

-"Explosive Round" instead of "Double tab". Your clone benefits from this talent too. Now you are even able to clear lanes!

-At level 20 i like "Double Strike" instead of rewind. This build is oriented to AoE damage and that's what your ultimate does, why not have two?

With this build you will loose some "selective damage" give that you wont have a second charge on your 'Pinning shot" and your snipe can be blocked by minions and your objective will only take 50% of its damage.
It is still worth it if you need the extra AoE in your composition.