I bought Leona Day 1. She's a pretty sweet tank. (MOAR LIKE AP CARRY, AMIRITE?!?!) She has 3 stuns, a gap closer, and a shield that gives her improved Armor and Magic Resistance for almost 6 seconds! What's not to love! As this is my first guide, it won't be perfect, but I'll try to explain things out, in a way I find makes sense to me, lol. Onward!

So... For runes... Get Health Marks, Armor Seals, and MR per Level Glyphs. Oh, and get a Quintessence of each to even it out :D

So masteries, get basic defense masteries like armor and MR, and then get the Health regen per 5 one maxed because that with Philo stone gives you cool guy regen at the beginning, so you can hang back and regen like a boss at the beginning. Makes it easier for you to help protect your partner early game and make the enemy wish they didn't try to attack your bro. Then get 2 points in dodge, cause we need them to get the last point in the tree. Get hardened skin and then Less damage from minions for easier harassment at early game. Then veteran's for the health boost, and then finally the 4% less damage cause its sweet. Then in the Utility tree, get the increased regen, followed by a point of less time spent dead. Then increased XP so your bro can kill people while you focus on keeping him alive. Then finally point in the increased gold so you can get stuff a bit faster.

Get a Regrowth Pendant first along with a health potion for the regen. You'll be regening like a boss, and probably not even need the potion. I barely ever do. Then when you get some money, and return to base because you have the money (Not because you need health, stand by the turret and regen!) buy your philo stone, and start your boots. Sometime later when you have the time, get a sunfire, then later either a Thornmail or Force of Nature, depending if the other team's heavy hitters are Magic or Attack dependent. Then get Frozen Mallet for health boost and slow on attack. Very good for helping your team catch runners. Then finally get Guardian Angel for the rez and good armor/MR.

Start with Daybreak, then get Eclipse, then Zenith. Max Eclipse first because the increased armor and MR is beast. Max Zenith second for the cdr on it, and Daybreak last. Take points in your ultimate wherever possible.

Get Ghost so you can run away if you get in too deep and your guys get focused down. Don't let them take down you too! And get Exhaust so you can slow guys down so your bros can get kills.

In conclusion, Leona is one of my favorite tanks. Give her a chance, and don't roll her as an AP Carry, no matter what people say. This build isn't, and won't be the best for Leona on Mobafire, or anywhere. Use it as a beginner's guide, take my suggestions with a grain of salt, and make it work for you. Have fun playing the newest tank in the League of Legends!