In the latest patch (up to date) Tristana got a buff on her E spell (Explosive Shot). Not only did it get more damage, but the duration got lowered for more damage in less time. I realized that with her 3 AP spells she could do massive damage by going AP. After having many wins in a row by carrying, i stated to wonder, is this just luck or is it a working build?

I'm going to update this build as many times as possible, because i haven't tried it enough to make it a completely working build, and i'm open for tips/hints from better players (i'm not the best player in the world indeed).

Skills
Rapid Fire

Rapid Fire is pretty much useless with an AP Tristana, even though it's pretty good for nuking towers/inhibitors.
Rocket Jump

This spell is your first spell and probably your last spell most of the times. It's great for both starting a nuke and escaping. The cooldown of Rocket Jump refreshes upon kills/assists, which makes it nearly spamable in teamfights.
Explosive Shot

Explosive shot is a Damage over time spell, and also a passive which makes your auto attack kills explode in an aoe. It's great for farming, and the DoT deals alot of damage, and is great for harrasing and finishing off.
Buster Shot

Oh my, this spell is just over powered. In endgame you will have about 500 AP, and if your target got 0 magic resist due to magic pen it will hit for 1000, which is quite alot. You can use it for both escaping and nuking, and in a smart way knocking them toward the team to start a nice gank. The cooldown is pretty small, which makes it one of the most usefull spells in this game in my opinion
Draw a bead (passive)

Makes tristana the champion with the most range ingame, not quite as usefull for AP as for AD, but can be handy.

Masteries/Runes
I'm going for ability power and magic penetration, because like AD Tristana she's a nuker. The masteries are simply just regular AP masteries.

Items
(Best starter item in my opinion)
(Magic Penetration = easy win)
(Duh)

those are allways my starting items, from here it will be a bit diffrent, depending on who you're up against:
(great for an extra slow against a fast person)
(Tristana got no heals, which means an extra heal could be usefull)
(Movement speed+Ability Power+Proc, could you need more?)
(Great for team fights)
(Is often an Endgame must)
(Can be used to get a better aim on Rocket Jump)
(Against tanks with 100 magic resist and above)
(Against AP nukers/people with more Magic resist than you like)

Summoner Spells

I picked Flash and Exhaust, but i'm still testing the other spells to find better results.

Flash: Easily my favourite spell, i can't live without it, good for both chasing and escaping.

Exhaust: Being as squishy as she is, she needs something to save her when she jumps into a group of people, hence choosing Exhaust.

I'm still testing out the other spell, and i will update the build if i find better options.

Pros

Her nuke is simalar to other AP champions, and deals massive damage.
She has imo the best escape mechanism ingame.
Rocket jump cooldown refreshes upon kill/assist.
Good both early/late
Healing reduction
Good harrasing spell (Explosive Shot)

Cons

Even with escape mechanisms she can be super squishy
Rocket jump can be hard to aim
Can be hard to play against a team with slowers and stunners

Guide

Starting off with a Doran's Ring gives you both health, damage and mana regen. early you need to last hit as much as possible, because with MP runes and explosive shot your passive will give you a chance to both kill another minion and harrasing the enemy champion. Try to harras the enemy as much as possible with Explosive shot, and if they come too close to the turret, simply rocket jump them and explosive shot them to force them to return to their base.

At once you have farmed enough to get your Boots, and hopefully a blasting wand/needlessly, you can start doing some serious damage to your enemy. Your rocket jump will do around 300-400 damage against a target with about 40 magic resist, and following a 400 damage dot + a 50 damage ultimate your target is easily dead. Make sure your enemy gets hit by rocket jump, missing it will make you an easy target unless you ulti them, which would be a waste.

If you're able to get Rabadon early, you're simply overpowered. Every rocket jump will deal about 30-50% of their health, and they will easily die to a W-E-R combo. At once you max up your ultimate it will deal about 800 damage to the enemy, and you will dominate the battleground.

Remember that timing is important. If you jump into a group of enemies and miss/fail, you will die cuz squishy unless you a miracle happen and you Buster shot the entire group.

I will update the Pros/Cons over the time, same with the guide.

Again, hints from profesionals would be really helpfull. I haven't played this game for too long, and some nice guidelines would be appriciated.

C&C is appriciated, have fun with her.