(This is actually my first time.) Leona is tank that can easily be one of the strongest character's against all the physical and magic user's. I've tried her in all ap build and dps build and I find it quite difficult in PvP. With her stuns, she can easily defend her team mates from a team battle and can easily fend for herself.

I would get the Greater Seals of Resilience for the armor. The Greater Marks of Fortitude for the Health and get the Greater Glyphs of Warding for the Magic Resist. I don't really have these runes since I started playing recently but after looking it up, I find these to be the best. I would Greater Quints of Resilience for even more armor.

Pros
-Very good at start
-Stun makes her best for laning with somebody
-Underestimated in damage since many people think a tank can't do damage
-Annoying to play against.
Con
-Relies on other Champs for the damage output
-Jungling is not the best for her
-Minions can take her down easily at the start

I chose a 0/21/9 Build to for a tank like her. I decided that dodge was needed but not to the extent that more movement speed is required. But other than that standard things I guess.

People say to start off with philosopher's stone, but I think Doran's shield is a good start. It allows more health, armor, and defense for the start. Then I get boots for speed, then chainmail for the armor. Then Giant's belt for the health and upgrade the boots to Mercury's. Then I would get the Sunfire for some damage output, then Aegis of Legion for the well balanced armor. I figured near Mid/late game that movement was a must that Force of Nature was quite useful, also for the magic resist. Then Frozen Heart for the mana needed to play Leona. then if there is enough time sell Doran's for Frozen Mallet for the Health.

I upgrade like any other Leona player Shield of David and Eclipse first. But at lvl 2, 1 round of Zenith Blade, then the rest is rotation of SoD and Eclipse. Getting Solar Flare when available. When attacking another champ, It's Activate Eclipse, Zenith Blade, Shield of David, and then solar flare and repeat without the Solar flare.

I find Clarity is quite useful, since as Leona, you spam her moves so much that mana a is must. Also Ghost is useful when ur tank's Health is no more and running away is all u can do.

I think that Leona is a great character for a support/ tank user like me. If ur not that type to support teammates, she can still be used just to help block attacks. She has the stuns to make her one of the strongest of all the tanks. Her farming ability is very good because of eclipse, and she can nuke anyone with all her skills.