Hi I'm Reaper Diana a support main that likes to play Diana mid. This guide is really fast, should be able to set up your build and learn the basics of this champ quickly as I doubt anyone with as little time as Ive got wants to read all this stuffs.

Landing skill shots is important but Diana has one of the more easier to dodge skill shots. In order to land this with near perfect accuracy use the minion creep block, its is a crescent shaped spell use the middle of it as the point you wish to target the enemy with and the detonation point as the spot where you think they will dodge toward. This requires you to be pretty close but it grantees it will hit its mark.

The laning phase will go pretty well most of the time as your Q has low mana costs and makes it easy for you to burn out your enemies biscuits. This next trick is the most crucial, its the trick that really nukes your enemy and makes them say "that's op" in chat. When you hit level 6, its usually the best time to just go ham. In order to maximize your destruction for an easy kill/flash you need to attack a minion twice and then land your Q on the enemy. By attacking a minion twice you have primed your passive for the damage bonus effect. Along with landing your Q you will have primed the enemy for a no cool down ulti.
AA MINION x2 + Q ENEMY + R ENEMY + AA ENEMY + W ENEMY + Q ENEMY + R ENEMY
This will be the maximum damage you can pull off on Diana and will usually destroy them.