Like in all my (and possible future) guides, I'll start focusing on the goals of the build, just to easily show the strong points I want to empower, and the weak ones I want to cover.

I start with 2 considerations:

1) Leona is a support/tank jungler, with a slow jungle-clear time, but with strong ganks.
About her slow jungle-clear time: her starting damage output is minimal and being an ap-based champion, classical jungle-items, like Wriggle's Lantern, will not appear in the build because Leona doesn't synergy well with.
About her strong ganks: Leona joins into that category of junglers that live with ganks[/color], and, her ganks are pretty strong thanks to the Zenith Blade+ Shield of Daybreak+ Sunlight combo.

So Leona has slow jungle-clear time, but it's compensated by strong ganks.
My goal is make them stronger.
Movespeed can be the key, helping Leona to easily chase and land Zenith Blade and Solar Flare.


2) Another important point to show about Leona, it's her presence in teamfights.
Solar Flare is perfect to initiate, Zenith Blade brings her in the middle of the fight, and Shield of Daybreak is a melee skill. It's easily to understand that Leona'll take damage how much time she'll stay in battle, so she has to be tanky.

In general her skillset makes Leona constantly being in team-fights.
Another goal is make her durable during the battle.


Goals:

• Movespeed will be covered with runes and masteries;
• Survivability will be covered with runes, masteries and items.

Here's the list of the runes I use to cover my goals:

Jungling Survivability:

• Greater Seal of Armor*9: are core runes, they give enough armor to safely clear the jungle.

Improving the potential of the ganks:

• Greater Quintessence of Movement Speed*3: +4,5% of movespeed helps anytime in the game, early to gank, mid-late to chase/initiate, never lost runes on Leona.

General Survivability, 2 choices:

1. Greater Glyph of Scaling Magic Resist*9: I preferred to use those runes before the patch because Leona's magic resist didn't scale on level, but with the new patch YES, it does.
2. Greater Glyph of Magic Resist*9: Now are more viable than Shielding one, before I didn't use them on Leona because she has Eclipse that provides more magic resist than flats Glyphs, and for early is enough. Anyway it depends also from the composition of enemy team, if it needs an early defense on magic resist, those runes are better.
3. Greater Glyph of Ability Power*9: if you agree with the previous statement about the magic resist provided by Eclipse, it's possible to use them for a better early damage in jungling and in ganking.

About marks I can be more flexible, having multiple choices with different rune-sets.
The viable ones are:

1. Greater Mark of Attack Speed*9: I use them to hit with an higher rate, just to clear a little faster, optimal for her;
2. Greater Mark of Attack Damage*9: +8,5 of damage helps to deal more damage to minions and in ganks, but Leona isn't supposed to be a damage dealer;
3. Greater Mark of Magic Penetration*9: Leona is an ap-champion, all her skills deal magic damage, investing into magic penetration isn't that bad during team-fights but suboptimal for jungling.

Leona needs to be pretty tanky (Survivability), with good mobility (Movespeed). The trees that can add defense and movespeed are the defense and utility one.

In defense tree there are unmovable points to set:

• Summoner's Resolve , 1 point: +10 gold smiting is must for a support jungler;
• Hardiness , 3 points: it's only for early game, helps during the clearing of the jungle;
• Tough Skin , 2 points: like above, and it unblocks Bladed Armor ;
• Durability , 4 points: +108 health at level 18 is good, but, more important the flat hp with Veteran's Scars ;
• Veteran's Scars , 1 point: 30 flat hp;
• Initiator , 3 points: +3% movespeed above 70% health, improving speed is a goal, we need to spend points for this;
• Juggernaut , 1 point: more health based on % it's good for end-game, the reduction of cc it's important in case of chasing and disruption.

With the 5 points left I suggest:

• Indomitable , 2 points: good early to tank minions' damage in jungle and ganks;
• Mercenary , 3 points: Eclipse it's a great skill, her aoe allows Leona to get many assists giving you more gold, that means more items;
• Evasion , 3 points: I prefer this instead of Honor Guard because Leona's a tank, rarely early focused but she'll take more collateral aoe damage;
• Enlightenment , 3 points: more cooldown, but I think the 15% one from Shurelya's Battlesong is already enough.

The 9 points left are going to be set in the utility tree:

• Summoner's Insight , 1 point: having reduction in Flash is always good;
• Improved Recall , 1 point: I like to spend 1 point to recall faster and save time;
• Swiftness , 4 points: core points, more speed.
• Good Hands or Expanded Mind , 2 points: are both pretty viable.
• Runic Affinity , 1 point: must for a support jungler.

Starting items, and early items are chosen to have a sustain while jungling.

1) Starting items:

1. Cloth Armor + 5 Health Potion: classic start;
2. Boots + 3 Health Potion: with a good pull at blue.

Likewise on which item you've started, after some recall, you need to have this set-up:

• Boots, or early Ninja Tabi or early Mobility Boots;
• Philosopher's Stone: Leona's jungle-sustain;
• Cloth Armor: from the start;
• Kindlegem: health and cooldown.

2) After this point it's possible to think about how upgrade the boots.
Viable options:

1. Mercury's Treads: good choice for magic resist and tenacity;
2. Mobility Boots: they are really good early, before taking Kindlegem and Philosopher's Stone. These boots make Leona's ganks really scaring, they are becoming my favorite boots;
3. Ninja Tabi: like above;
4. Ionian Boots of Lucidity: they are good, but don't bring any sort of survivability, and having a Kindlegem next to a Shurelya's Battlesong, they are a waste.

3) It's time to prepare Leona for team-fights building up her core items:

• Giant's Belt into Sunfire Aegis: helps to clear the jungle faster and allows Leona being tanky in team-fights dealing extra aoe damage.
• Shurelya's Battlesong: helps to have early sustain in jungle, and later to initiate;
• Ruby Crystal into Aegis of the Legion or Locket of the Iron Solari: both these items are composed by the starter Cloth Armor, they are both really good and cheap, but if you are going to build Locket of the Iron Solari, I suggest to have a Heart of Gold already bought previously, maybe before Shurelya's Battlesong and Sunfire Aegis.

After building core items, Leona'll have about 3000 hp with really cheap efforts.
Side note: with Shurelya's Battlesong and Locket of the Iron Solari, Leona 'll have 65 health regen at level 18.

4) From now on it's possible to focus on defense or also damage with end game items:

1. Abyssal Mask: if magic resist needed this item synergies well with Leona, she's ap;
2. Trinity Force: yes, trinity force, not a "must have" item but make Leona faster, durable and deadly; take Phage like first item, if you wanna build this item;
3. Randuin's Omen: not that cheap but pretty strong vs an ad-based team, it can replace Locket of the Iron Solari if not previously upgraded Heart of Gold.

5) And then remember to take Elixir of Agility, Elixir of Brilliance, Elixir of Fortitude, Oracle's Elixir.

First skill to take and maximize is Eclipse, toclear the jungle faster and be tanky with a fixed cheap mana-cost.

The second skill is Zenith Blade because it deals a sort of aoe damage, usefull to clear more than 1 minion at time. It will be the second skill to maximize because has a fixed cheap cost of mana.

At level 3 chose if take Shield of Daybreak for an early gank or wait level 4, it will be the last skill to maximize because it has an increased mana-cost.

Every time is possible level up Solar Flare.

Whenever, after maximizing Eclipse, Leona has enough manapool to handle the increased cost of Shield of Daybreak, so after that point it's possible alternate the leveling of Shield of Daybreak and Zenith Blade to have better synchronized cooldowns.

This will be a tiny part of the guide.

One summoner's spell is a must:
Smite: clear faster, more gold, ability to steal important dragon or baron.

The second spell can be:
Flash: really good in defense to back over a wall, in attack to follow someone over a wall, to make some tricks like Flash + Shield of Daybreak / Zenith Blade / Solar Flare combo;
Ghost: viable spell to improve speed and chasing better.

Leona is a cc machine, 3 skills of 4, block/stun the target making her ganks really strong.
2 of them are good to initiate teamfights.
Also the mana-costs aren't so high, making her perfect to jungle.

In this guide, I hope to have clearly explained my point of view about Jungler-Leona, and why I have taken some rune/mastery/item instead of others.