This guide is very much a work in progress. Will need lots of feedback from more experienced Leona players to really make this guide great or to see if its even viable competitively. Will be following up with screenshots, better looking guide, and possibly a youtube if there's enough interest. Please forgive any Warcraft Warhammer Diablo LoTR or any other nerd references I will undoubtedly use throughout.

Update 1.0 4/22/12: Changed masteries to utility, changed end item to abyssal scepter, removed more offense minded endgame options, updated relevant sections, changed cdr marks to flat hp.

ON WITH THE SHOW!

Welcome summoners! Leona is a fantastic champion that is traditionally played as a bot lane tank paired with a bursty dps. The early dps from your teammate combined with Leona's fantastic cc turns bot lane into a kill lane. My Leona functions essentially the same way but instead of going pure tank late game we're going to focus instead on items that benefit the entire team with auras, item abilities, and debuffs.

PROS

Very Tanky
Has Fantastic CC
Gives great stats to team
Can shrug off turret shots
Rewards aggressive behavior
Relatively cheap core build and multiple gold per five frees up cash for wards or oracles.
Is a solar powered paladin (possibly Tauren in disguise)

CONS

Can't solo worth beans
Early levels can be surprisingly squishy
Reliant on teammates
You will be tied in damage with support Soraka

Sunlight is your passive. Every time you hit an enemy with your spell it applies a debuff to them. Upon being attacked by an ally the debuff is consumed and the enemy is dealt 20 / 35 / 50 / 65 / 80 / 95 / 110 / 125 / 140 additional magic damage. This passive can really rack up the damage fast and is a great support passive as it increases your carries dps.

Shield of Daybreak Your next autoattack will deal additional magic damage and stun your opponent for a brief time.
Cost: 45 / 50 / 55 / 60 / 65 mana
Cooldown: 11 / 10 / 9 / 8 / 7 seconds
Magic Damage: 40 / 70 / 100 / 130 / 160 (+0.3 per ability power)
This skill is pretty self explanatory. Cheap and spammable. Can be used to last hit if necessary.

Eclipse is an amazing spell that makes you damn near unkillable for the duration and deals a solid amount of aoe damage at the end.
Cost: 60 mana
Cooldown: 14 seconds
Radius:
Armor & Magic Resist Bonus: 30 / 40 / 50 / 60 / 70
Magic Damage: 60 / 110 / 160 / 210 / 260 (+0.4 per ability power)
Max it first and use it whenever in danger or farming a minion wave.

Leona will hurl her Zenith Blade in a fast moving medium ranged line skillshot that does damage to anything it passes through. Leona will dash to the last CHAMPION hit by the blade. This is her main initiator. Useful for chasing as well.
Cost: 60 mana
Range: 700
Cooldown: 13 / 12 / 11 / 10 / 9 seconds
Magic Damage: 60 / 100 / 140 / 180 / 220 (+0.4 per ability power)
The blade has a width similar to nidalees spear and can be tough to hit if not practiced.

Solar Flare is Leona's ultimate.
Range to Center of AoE: 1200
Radius of Damaging AoE: 250
Radius of Stun AoE: 100
Radius of Sight AoE: 700
Cost: 100 / 150 / 200 mana
Cooldown: 90 / 75 / 60 seconds
Magic Damage: 150 / 250 / 350 (+0.8 per ability power)
It's an aoe skillshot with a good range. Everyone hit dead center will be stunned. Everyone on the outskirts of the decently sized nuke is slowed. Great for chasing, initiating, kill stealing.

I like tank masteries but some will find utility to be the better choice. Pick whatever you feel works for you.

I recommend some form of armor seals with magic resist glyphs. Flat hp quints help with the level 1 squishy blues and lets you be aggressive from the get go. I leave the marks to your own discretion... flat health never hurts.

Skill sequence gets your initiate/stun combo up at level 3 and then has you max your Eclipse first. I like leveling Zenith Blade at the same time as Shield of Daybreak. As usual put points into your ultimate Solar Flare as they become available.

Summoner spells..... I use tele and ghost on almost all my chars so I won't even begin to give advice here but it's been suggested that exhaust or heal would fit her better. Do what you want imo. Flash is tried and true.

Core Items

Regrowth Pendant gives you solid early sustain and will be built into the ever so useful Philo stone for gold... and even MORE sustain. This is the only mana regen you'll have until late game Soul Shroud but fortunately it's all you really need.

Mercury's Treads are pretty self explanatory. Tenacity is fantastic in this game especially for any melee. The magic resist rounds out the armor you'll soon be getting from Sunfire Cape nicely.

Heart of Gold gives you both health and gold which are both good and needed on Leona. We will later be turning this into a Locket of the Iron Solari.

Aegis of the Legion is a crazy efficient item and helps your team immensely. Were'nt feeling tanky with just your heart of gold? You will now. Cheap to get and is an enormous F**k you to the enemies teams carries in teamfights. Hybrids will nash their teeth at your perfectly balanced defensive stats.

Sunfire Aegis Nothing says COME AT ME BRO quite like a sunfire cape does. A solid chunk of health and armor combined with an aoe damaging aura will make people think twice before jumping into the fiery meat grinder. The fact that it meshes well thematically with a sun paladin is just gravy.

Locket of the Iron Solari will turn you into a full fledged support. You exude an aoe HoT (heal over time) from yourself and can proc the shield for surprisingly good absorption. This is yet another item that gives you a chunk of health. You'll find that at this point it has added up and coupled with your fantastically high resists and tenacity will also allow you to stride across the battlefield doing your thing while your enemies are forced to either focus a 3k health Leona with 200 armor and 118 magic resist (before eclipse is even factored in or get raped by your buffed teammates and constant stream of stuns/debuffs.

Soul Shroud Yet more health and another aura for teammates. The CDR is very important as well though. To get the most out of her stuns she needs to be able to spam them. This will help you along this path.

Situational Endgame Items

Abyssal Mask gives you more magic resist, an enemy debuff and a little bit of offense in the form of some AP. Solid item

Possible replacements include:

Shurelya's Battlesong If you feel like you need a bit more health and less magic resist you can just turn that philo stone into a cheap shurelya's and get a nifty speed boost activate in the process.

Getting wrecked by AD carries? Show your teammates you care with a Frozen Heart.

Getting wrecked by AP carries? Force of Nature may be the nail in their coffin.

STILL not enough auras for you? Get a Zeke's Herald or Will of the Ancients depending on your team comp for epic team sustain that will keep a push going and going.

If you really must sacrifice some cdr from your late game build consider Ionian Boots of Lucidity.
If your opponents are all ad then Ninja Tabi will give you a huge early game survivability boost for cheap.
If your opponents have virtually zero cc then Boots of Swiftness may help an otherwise slow turtle become a speedy stuntastic meatshield of a hare.

Are you getting focused every teamfight lategame because of how much pure winsauce you bring to the table? Cash in that old and busted Aegis of the Legion and upgrade it to the new hotness Guardian Angel.

Why support Leona? It will help to compare it to the three most commonly seen builds; AP Leona, AD Leona, and Full Tank Leona
AP Leona provides you a little burst but it's probably the least optimal way to build her. Sure her abilities scale off AP but they do so atrociously with a ratio of .4. If that sounds godawful it's because it is. Leona isn't a Mao/'kai or Amumu. She's best for taking damage to the face but not dishing it in return.
AD Leona provides better sustained damage and scales better than AP. Additionally, it may seem that AD Leona is the best choice given how much inherent cc and tankiness she has built in. However to get the sort of damage you need you usually have to build squishier than Leona should really be and at the end of the day you won't be doing anything that a Sion or Jarvan couldn't do a hundred times better with the same items.
Full tank Leona is probably the most popular and that's because she's a natural damage sponge with lots of cc. The problem with Leona is that to be an effective tank you need to do at least two of the following three; provide hard cc like taunts, provide sheilds to allies, and provide enough dps that you're a threat to squishy carries. You don't gain aggro like in wow. If you are doing no damage then the other team will just ignore you like they would a full tank Garen or Mundo. Compounding the problem is the fact that compared to other tanks Leona's cc is also sadly lacking. She lacks a taunt or aoe hard lockdown that Galio or Amumu or Rammus possess that make them so great.

Which brings us to Support Tank Leona.

It was a problem that I had a long think on. What do you do with a tank with no threat? How do you make a contribution besides a few interspersed stuns and snares if you're unable to do damage? Then it hit me. Stop trying to do damage altogether and refocus that itemization to something more productive. A melee character with good cc, tankiness, great team utility, but piss poor damage. Sounds a bit like another paladin we know doesn't it (think geologically)? A paladin that is played as support. But Taric can heal allies and brings more to the table than his stuns and tankiness. You're going to make up for that in the auras you bring to your team and in the end you're going to be a veritable fortress to dash enemies upon and a beacon of strength and l337 buffs for your allies.
The debuff your passive provides along with your low priority beefiness along with your stuns and cc along with your laughable damage output along with a subpar jungle forcing you to go lane... well all this screams support to me. You'll still behave and act the same way full tank Leona does but you'll have the utility that will greatly aid the people actually being focused and actually doing damage instead of just standing around stamping your feet like a shiny ****** in between cooldowns as your team gets bursted around you. Give it a shot. I think you'll find it's a blast to play.

*Note* Doing no damage, you'll never have the highest kills in the game but you're so tanky that your deaths will be few and far between (something an enemy twitch will learn to regret as one oracles lasts you half the game). It's not uncommon to end up with a score resembling 5/3/23

Lategame Leona is a brick wall. Level 1 Leona on the other hand is just as squishy as anyone else on the field. Eclipse mitigates this somewhat but play passive for the first levels and hope that the carry you're with can harass decently. Don't engage unless you know you can win. I won't say zero farm but try to let your carry get as much as he can.

Once you get to level 3 you can start going in on people and start playing a little more aggressively. Between your partners high damage, your substantial stun and cc, and the low starting health of enemies, you can usually get first blood. If they've overextended don't be surprised at a double kill for you and yours. Zone out enemy players whenever you can and generally be the boss dog of whatever lane you've honored with your presence. Remember that Leona is safe at almost any level of health if she's under a turret. Diving Leona and her stuns is suicide and she has a good chance of surviving thanks to Eclipse. Conversely, later on Leona can initiate teamfights under enemy towers with little fear due to her chunkiness.

Once someone's turret is down in your lane you can start roaming. Teamfight time. You may want to delay this if possible as forcing teamfights at the 10 minute mark may hinder your team more than help but that's for your judgement.

Mid game you're now fairly tanky with Aegis and maybe even Sunfire. Number one rule I can say is don't go it alone. You can't solo anyone so you're just a free kill if caught alone but put you next to an ally and watch the magic happen. You don't farm the jungle. You dont split push by yourself across the map. You just sprint towards every single teamfight you can find and push alongside allies when its time to push. (though this goes for every champion in general it goes double for Leona).

Lategame is conveniently much the same as midgame except better. Run around teamfights stunning carries, locking down, escapees, and trying to stay on the nuts of the squishiest thing within reach. Don't forget item abilities as well. If doing well buy wards or oracles or whatever you need. If doing poorly .... buy wards or oracles or whatever you need. Lategame Leona is the Rock of Gibraltar and can tank inner turrets like they were nothing. If you have someone with high dps, you and him can just backdoor all day no minions required. This is one of reasons I often roll with teleport.

I'd like to thank people in advance for constructive criticism. This is a work in progress so it will require rigorous testing. If I could get some high elo ranked feedback it would be great as well.

Special thanks to Jhoijhoi for helping us noobs cobble together a half decent build guide since 2011.

Making a Guide by jhoijhoi