Hey guys my first build and its two team builds one Bursters one Off Tanks. The info under this may not be so good because I'm not that good at this stuff. But anyway.. Enjoy!!!

Hp and Mana pots
The reason I would go with Two hp pots and one mana pot, is because as Darius lane killing should be easy and should lose a bit more mana than hp using his abilities.

TriForce and Frozen Mallet
I know the slows don't stack I'm not stupid but the sheen from the TriForce works great with each of your abilities. even though the slow is non existent on the TriForce the rest of its buffs are good.

Infinity Edge
The reason for Infinity is right in front of you I guess. You have the TriForce already giving some crits so why not get an Infinity. It even gives more damage!

Null Cloaks
The reason of getting three null cloaks before anything else is. One - It gives good magic resist. Two - Galio's passive gives him more ability power percentage of his magic resist.

Items from null cloaks
Tell me better starting items for a mid lane with only those three items.

Heart of Gold
The reason for not going for a few wards is that as Leona you need to jump in a save your teammate.

Wards
I know you might think its weird buying wards like this, well basically when ever you go back to buy an item is to buy a few wards. Thats what I'm trying to show.

Ad Carry Gang Plank
Yes it may sound stupid but it can work with a cc champion like Leona or Blitz Crank because they can hold them there and let Gang Plank hit on them, and even Gang Plank as his own cc hes got a slow and also a movement speed buff.

Ganking
When you gank try and use your Safe Guard to get close to your enemies then use your Tempest Smash and then use your Sonic Wave you get to them if they flash or blink away. If you can ult them into your team so they can be killed easer.

Warmogs, Atma's Impaler and Force of Nature
You want to be tanky, but deal damage. Your TriForce also goes to your Atmas just a bit probably 5-15 damage but its still good. Force of Nature also gives you good magic resist to ageist the mages late game.

TriForce
Do I have to say? He has Seven Abilities...

First Blood
As Firoa you want to try and get First Blood because of the great burst she has. By level two get your Parry giving you plus 15 damage, making your flat damage around 100 when you hit level two jump at your enemie and parry an attack (It does great damage) and you should be able to kill him if you harrased him at level one. If your team is playing more defenive then wait till level three. Get your Burst of Speed then jump at them with all your abilities and you should get First Blood.

Blood Thister and Wriggles lantern
Getting these both as your first items gives you great - Life Steal, easlier to kill minons, a ward, good damage. Thats about it, in your ult you gain your on hit effects even Life Steal, so after your ult is done you should of gained 100-300 hp back with Life Steal.

Frozen Mallet
Your ult gives you on hit effects so even Frozen Mallet works with it,

Ganking
When you hit level six try and gank bot lane for an easy double kill. If your lucky they wont have flash and even their jungler could be there.

Basics
Just do your combos right, I'm no good at Diana never played her but been owned and owned with to know enough about how she works.

Support and Harras
When your adc needs it heal or give him mana, when he does not harras the enemies using your starfall+basic+silence for some great damage.

Wards
I know you might think its weird buying wards like this, well basically when ever you go back to buy an item is to buy a few wards. Thats what I'm trying to show.

Poke
Just poke, poke, poke really and when there low enough jump in and wreak them at close range, if the flash just use your second flash if up and you should get the kill.

Ult
Of course your gonna wanna try and snipe someone down or just take down a minion wave.

Ganking
When ganking you want to either use your E to stun with the five stack to stop them from getting away or use your five stack with you Q for heaps of damage but only if you can get that on them.