Hello everybody, welcome to my Mobafire Leona build and I wish you luck and succes in playing her with my build. :)

Actually there are few ways to play Leona The Radiant Dawn.
My favuorite build for Leona The Radiant Dawn is pure tank.
She has very big resistes ( armor and magic resist) at same beginning. That is her special.
Her passive is on spellcast at enemy she marks it ( it is similar to Lux's passive) and her teammates make her on casual hit massive extra magic damage.
You can either play her like full mage. Her spells take 100% of Ability Power or shortly AP.
That is medium way to play her.
And there is a way to play Leona like hybrid between mage and tank.
It is medium to hard way to play her.
But in that case if you play Leona like hybrid you will have choice to buy her first or tank or AP items. I recommend You if you have jungler in team to go solo lane and buy tanky items first. Good luck. :)

For my runes i take 9 Greater Marks of Fortitude. I take them because I need HP at same start to be strongest on map.
Greater Seal of Resillience I take for armor, which you need if you lane vs Nocturne or Master Yi or any other melle dps champion.
Greater Glyph of Warding You need if you lane vs Brand, Lux, LeBlanc or any other MAGE champion.
For Quintensences i take Greater Quintensences of Fortitude for Health, I want to have most HP on map as I said on Marks. With 110 HP in same start + If You want Doran's shield you will have about 1000 HP , a bit less but almost 1000. That is VERY good if You want to tank her ^^.

About masteries I can't tell much. It is only mater that masteries are focused on defence!!! :)

With Leone team work is very important. You must use your passive as best as you can, that will make enemy team healthless in no time. In late game you must use your stuns right way, try to focus squishy targets like Anivia , Ashe, Ezreal and such. When you get stun on them use your ultimate ( ONLY IN TEAMFIGHTS) and try to hit as much enemy champions as you can. That will allow you and Your team to kill them fast.

Farming isn't very important with Leona, try to give farm to your teammates.