Hi and welcome to my AP Mid Tristana guide! I made this guide because you don't find a lot of AP Trist guides out there right now, and I hope this gets you what you need for AP Tristana :)! Like if you Enjoy!

I chose the runes for max damage and some sustain in lane for the MR and Mana regen. You can go flat MR or MR/Per level, whatever you prefer.

I find these the possible best for AP tristana. these masteries help with Burst (AP/MagicPen) Sustain (ManaRegen) and for the duration of blue.

This is one you can kind of have a variation. If you prefer Guardian angel instead of Zhonya's hourglass then so be it. If the enemy stack MR get the void staff, if not Lich Bane. Rush DFG ASAP. ALWAYS Start boots with pots.

if you are invading start W. Lets you catch up for First Blood on kill, and lets you escape with ease. ALWAYS max R of course, q is well, useless other than pushing towers or farming lane hard or jungle.

Skill priority: R->E->W->Q
Optional skill priority: R->W->E->Q )if you prefer W over E for damage)

Flash/Ignite is without a doubt the best. With W Combined with R + The flash = Ungankable.
If you prefer you can go Exhaust/Ignite or heal/Ignite they both work.

Rocket Jump: Try and land these on big team fights, where you can get as many enemies as possible, use this safe though because if you jump alone your F*****. If you need to secure the kill with this since it resets on assist/kill. Jump in Jump out, Simple.

Explosive Shot: Very easy way to poke enemy mid champ without being poked back. W->E to run is a good way to poke.

Buster Shot: Main reason I go AP. INSANE amounts of damage with a knockback, use this to push enemy into team with combo of W->R, Or secure the kill with this high dmg ult. If you want to tower dive W-> R just for the damage, jump in range and BOOM!

Pros

-High damage
-Very Fun
-Nice escape With R+W+Flash

Cons

-Squishy as AP
-Harder to CS than AD
-Get focused :(

passive is pretty useful for this, easy to clear mobs with W+Passive, Safer clearing as well.