Hello! Welcome to my Leona Guide! Leona being a new champion, some may need some guidance to build Leona. I'm absolutely not qualified to write this guide (I'm unranked/no ELO) but I have have had some success with this build. Please comment and criticize on this build, so I can improve it and make it better.

Besides, there's no harm in trying it, right?

So let's get started.

Pros
Lot's of hard cc (stuns)
Really fun to play (subjective)
She can peel people off EXTREMELY easily.
Pretty clear-cut skill combo.

Cons
Does insignificant damage late-game.
Team-dependent
Relies on items to tank effectively (like Amumu)

I don't know code, so here goes...

x9 MR Marks
x9 Armor Seals
x9 CDR Glyphs
x9 Health Quints

The CDR seems a bit out of place doesn't it?
Leona is a champion that relies a lot on her skills. Without the CDR from runes, you will be unable to achieve a CDR that gives you a stun every 5 seconds at max level. Otherwise, go standard tank runes.

Flash: Good, a personal fav.
Teleport: Also a personal fav.
Exhaust: Meh, mostly used on offensive classes.
Ghost: Also good, a useful spell.
Smite: Only if you're jungling...
Clarity: She can be a bit mana hungry, but she's not THAT mana hungry....
Heal: Take it if you're not comfortable with a regrowth and 1 pot.
Rally: Meh.
Cleanse: Again, meh.
Fortify: You COULD.... but that would mean giving up another summoner. However, it is viable.
Ignite: Mostly for offensive classes. Meh.
Revive: If I ever meet you in game and you have this, I will bawl my eyes out. Seriously.

Solar Flare -> Shield of Daybreak -> Eclipse -> Zenith Blade

OR

Solar Flare -> Eclipse -> Shield of Daybreak -> Zenith Blade

Leveling up ult is a no brainer. The big choice is whether to take Shield or Eclipse first. If you have a strong carry or cc in your lane, take Shield. If you don't take Eclipse. In my opinion, it comes down to personal preference. Personally, I like taking Shield first for that sexy stun every 5 seconds w/ CD. However, Eclipse is strong early game when you don't have a lot of item-based resists, so it's also viable. You can also try Zenith first, but I don't recommend it, as you won't have enough cc to back it up.

9-0-21 Masteries. Take all of the CDR masteries. Nuff said.

"Wait a minute!" you may be saying. Leona's a tank! Don't you need tank masteries?!

Well, remember Leona's role. She's supposed to initiate and lock down the carry. She can't do this w/o her skills off CD. Obviously, she need CDR. Problem is, That CDR is only located in the Offensive and Utility Mastery Trees T_T. Fortunately, I find that Leona can tank just fine with items, even without the masteries. However, there aren't a lot of items with CDR AND tanking capabilities. This Leona makes use of the ones that have both.

Before we get down and dirty to the item build, I want you to understand how I understand tanking.

To me, a tank is a large, strong man with bad-*** armor.

The strong man is a metaphor for HP.
The armor is a metaphor to resists.

Let's look at an extreme armor tank.
He's a small boy, but with massive amounts of armor. He's not going to get cut anytime soon, but you can just kick him away and he's no more.

Now here's an extreme health tank.
He's a spartan, being giant and bad-***, but has no armor. What's he going to do when someone throws a spear at him? Dodge it? (Jax)

By this metaphor, I believe that a tank needs to have VERY beefy HP, but also with decent resists. I remember this:

1. HP lets you live.
2. Resists reduce damage by a percentage.
3. Resists have an imaginary diminishing return at some point. (I'd say at about 150-200 resist or so.)
4. At the point where you hit diminishing returns from resists is where you build HP.
5. Or vice versa.

Therefore, this build will focus on getting Leona to get a healthy balance of HP and resists.
WAIT WHAT ABOUT THE CDR!?
Ah, this is where everything comes together. While you are getting the tank items, you are also building a high amount of CDR. Reference the build to see.

CORE:
Philosopher's Stone
Ionian Boots
Kindlegem
Aegis of Legion

EXTENDED:
Warmog
Spirit Visage
Force of Nature or Frozen Heart, depending on their team comp.

I know, I know, not many people like the Warmogz. However, the fact that it gives over 1k HP fully stacked is quite a large HP boost. To give it a scale of how much HP it gives, it gives about twice the amount of HP from Frozen Mallet for less cost. Sure, Frozen Mallet gives 20 AD plus a slowing effect, but that extra 700 HP shouldn't be neglected. Remember, you have to be a big strong woman. A warmog can help you achieve that with just one item.Sure, you can build HP plus resist items, but just how many items have magic resist AND HP? That's right, just Banshee's Veil. And just.... Wait a minute, you can just swap Force of Nature and Banshee's Veil if you want to. To be frank, you can adjust this build depending on the resists and such. Nevertheless, I like the warmog for it's massive HP gains.

Now you might be thinking: "Why doesn't this build build a lot of resists?" Well, Eclipse makes up for that. getting an extra 70 armor and magic resist is like getting a free super negatron and chain mail for 3-6 seconds. Pretty nifty for saving space and money in your inventory.

Early Game:

Suprisingly, Leona can put out some decent early game DPS. Pair up with a strong early game carry or another cc for nice results. The stuns lock down one person to kill.

Mid Game:

People should be ganking and pushing towers at this point. Initiate teamfights and stun lost enemies when you can. Try to stay with your team, as Leona can't 1v1 for her life after her CDs are done (not counting AD carry Leona).

Late Game:

Do pretty much the same as mid game, except you should be much more capable to tank damage.

Activate Eclipse, initiate with Zenith, stun carry with Solar Flare and Shield.

Pretty Simple.

While your carries are wailing away on the opposing team, you should be locking down the enemy carry with your constant stuns. That way, he/she won't kill your team.

You can also take the more defensive role, and peel the people off your carries.

This guide focuses on building Leona a CDR tank, with good capabilities in tanking, initiating, and protecting.

If you don't like this build at first sight...

Try it in normal mode for a few games, then rate.

What have you got to lose?