This is the build I like to go when playing Leona.
This build costs a lot of money but it pays of when u get long games.
Don't try this build when your team is getting downed, you'll want to go a more armor and magic resist related build for those games, which are cheaper.

Reds - Armor Pen for Trinity + Auto Attacks. Magic damage in all your skills but the most damage will be comming from trinity, auto atks and in late game a lot from your atma's impaler.

Yellows - Flat Armor for a stronger laning phase

Blues - Flat MR for a stronger laning phase

Quints - Flat HP for early game lane presence. --> no Health regen as your warmog's will be giving a lot of Health regen later on.

0/21/9 - Using the standard defence points ( no dodge ) with 9 points in Utility to give extra exp gain in your lane.

Here are the items I use and why I use them.

Regrowth Pendant + HP pot - Health Regen for the lane durability.

Philo Stone + Ruby Cristal - Extra Health Regen + Mana Regen from Philo and Health from your Ruby cristal. The Mana Regen is usefull as the skills Leona uses are best while used in combination with eachother.

Boots + Heart of gold - Boots for speed to get back in lane and evade skillshots. Heart of gold to bring gold income to 10G/10Sec.

Sheen - Sheen is perfect to be used in combination of her skills, as you stun your target u deal extra damage thanks to the Sheen's passive ability.

Lucidity Boots - I prefer these boots for the cooldown reduction, the cooldown reduction helps a lot in teamfights as you can use your combination atks more often.

Warmog's armor - This gives a lot of HP when bought and even more when it has it's charge. This bunch of HP and Health Regen will be the base of your durability and damage in the late game.

Phage into Trinity - Buy the Phage first for the extra Health and the slow your atks give. Later you buy the full Trinity.

Atma's Impaler - Leona has just a little over 4k Health now so the Atma's Impaler gives a very nice damage bonus to Leona's auto-atk. After the full combo of Leona's spell the auto-atk will have a nice 200+ hit ( + some crit chance. )

Force of Nature - Force of Nature as MR as the most damage taken in teamfights will be magical and because of your high HP you gain more Health/sec from the passive of this item. This in combination with the 2nd skill gives as very nice MR with Armor aswell.

Shurelya's Reverie - Great speed boost for initiation or for an escape with teammates in danger. Also more HP.

Max 2nd skill ( W/Z ) first - I get W first as it offers protection and damage. It helps a lot clearing minion waves and reducing incomming damage. W can also be used in combination with E to clear minion waves even faster ( I advise standing between melee and mage minions to hit them all. )

Max 3th skill ( E ) next - Since maxing Q ( A in azerty keyboards ) offers nothing more than some damage and a lower CD I advise maxing E next as it is also a ranged atk. This atk deals a nice amount of damage and has an AoE. This skill in combination with W is perfect for farming minions.

Max 1st skill ( Q/A ) last - Offers some CD reduction and some extra damage. U don't need it at an higher level until everything else is maxed as it DOES NOT give you a longer stun.


NOTE: - when planning gank at the start of a game get your first skill first and your 2nd skill later at level 3 after gettign zenith blade on level 2. The stun from your first skill can be very powerfull when planning early game gank ( in the enemy jungle? ).

Flash - Flash is just an overal good spell to escape or the engage.

Ghost - Also good to escape or engage but Flash is advised over Ghost.

Exhaust - This is a perfect spell in combination with flash as engage as u can use it on the enemy's DPS or Mage. Also good to chase enemy champions early game in ganks.

Ignite - This can be very powerfull in combination with the full Leona combo. She doesn't look dangerous because she's a tank but she knows how to give a punch.

Clarity - You must be thinking, why would someone need clarity when playing Leona. Well: I find this rather usefull early-game and even in the mid-game. When using clarity you have the ability of using your spells more often for lane dominance and you can cast it to recharge friendly champions aswell. This spell is not advised in organised ranked play.

She can be used in ranked play but don't overextend with her or think she's all that easy.

The hardest part will be getting the farm on and surviving in the early-game, after that you should be able to go your build and be fine.

Ganking in Leona's lane can be very succesfull thanks to her passive which deals extra damage when teammates hit the enlighted target. Her CC are also very usefull to delay an escape and giving you more time to kill the enemy champion.
So jungler's, gank this lane.

PRO

- A lot of CC
- Spells work in perfect combination with eachother
- When you can finish this build -> awesomeness
- Perfect to initiate teambattles

CONTRA

- She's weak in the lane on it's own
- Rather slow movement speed to start with
- Some basic stats could use a buff

Leona isn't made to stand in the jungle, so I advise not to :D

You can always try jungling with her but you will have more succes using jungler champions.

This is Leona's strong point. Her entire beeing is based around team play. Thanks to her passive ability ( that deals extra damage when teammates hit targetted monsters/champions ) she deals a nice extra bonus damage in team fights.
Thanks to her stun/engage combination spells she's perfect to initiate team fights.

The combination I use to engage is:
- Activate the Eclipse spell ( W/Z )
- Activate the Shield of Daybreak spell ( Q/A )
- Then use the Zenith blade ( E ) to engage in fights ( make sure to target the enemy champion for your stun.

With proper timing the shield should explode right after the stun has worn off and give a nice bonus damage to add in the fight.

Use her 2nd ability 'Eclipse' ( W/Z ) to deal damage to minions and use the 3th skill 'Zenith Blade' ( E ) to finish the minions off from a nice range.

Laning with Leona can be difficult but when the income grows the better it gets.

- In the Solo lane you get a nice income as you don't have to share minions ( non ranked play there might not be a jungler so 2 people in top lane is possible. ) When leona is allowed to go this build it will be awefully hard to take her down in the late game as a Fed leona ( minions or kills ) is a force to be scared off, especially in team fights.

- While Duo-laning with Leona ( Non Ranked ) you will want a ranged carrie by your side as I feel this combination to be rather dangerous for the enemy team. This thanks to the passive ability for that extra damage which can be activated from a nice safe distance.
You don't want to duo lane with a support, as you will get downed thanks to a result of to low damage.

I hope you find this build rather usefull ingame and enjoy playing her as much as I do.

I got the inspiration for this build out of Elementz his Leona build called 'Finally some female tanking n spanking!'
I added the Health part in combination with atma's impaler as I like to play as tank but still do damage for the team.
This build costs a lot so you won't be able to go this build every game, but when you feel you can farm a nice number of minion you should be able to get this build.
-> 1 problem you say? Less armor and MR?
* I agree but thanks to the 'Eclipse' spell ( W/Z ) you gain 30 armor and MR from lvl 1 in that skill and will gain 10 in each for every extra level. Since her 2nd skill should be maxed first there will be no problems in the Armor and MR departement.