Tips for Leona?

As with all tank supports, only all in when you are certain your adc can back you up or the jungler is coming. I just use a basic rune page for all my tanks. 3x Armor Quints, 9x Seals of Scaling heath, 9x Glyphs of Scaling Magic Resist, 9x Marks of Attack Speed. Just what i use, but its up to what you prefer. Oh and for tank support masteries i use, Cunning: L,M,R,L and Resolve: L,R,R,L,R,R

I've seen Leona jungle but it's not that good

Leona serves two purposes in lane: to kill the enemy bot lane, or if that isnt possible, to be the bodyguard of your adc. First thing of order is that you want to get your w at lvl 3, but max it first because its defense steroid and damage both scale well. Your main source of damage is your passive, which requires an ally to deal damage to activate, therefore requiring leona to have a partner to trade optimally. Leona is one of the few champions that can kill wards by herself without a scanner trinket: if an enemy drops a ward near you just auto- q reset- click again to auto to kill it. The highest damage combo leona can do in lane phase is w-e-auto-q-auto(w detonates at this point). If you have ult then you use that last. If you feel that you simply need to cc lock the enemy do not auto reset, just smackem with that q so they have no time to flash. Damage over time like cass q, twitch passive, and teemo poison all proc your passive. So if twitch so much as lands a single auto onto the enemy, you can literally proc all of your passive procs when you go in by yourself. If you feel that you are unable to land your ult or e on a priority target(ie kalista) at a critical time (like if your jungler is coming in for a gank) you can either flash q for the instant stun into free ult stun or exhaust them from the very beginning so you can land your skillshots easier. Like nautilus, Leona does not always have to initiate with her ult or e. If the enemy bot lane is allowing you to walk very close to them you can simply close the distance by walking up and then q in their face. Leona is an excellent roaming support due to her ability to initiate fights from range. Leona is able to both initiate fights and peel for the back line at the same time: save your ult when initiating if you think some guys from the enemy team will try and dive the back line so you can peel them off with that huge range on the ult. Like any tank, Leonas build is dependant on what damage the enemy team has, but the sole core item of her build outside of the support item is locket of the iron solari, though im sure some others build differently. For masteries I personally go with 0/12/18 with Bond of Stone (Its really the only mastery that matters, anything else is preference) For runes I go with AD quints and marks, armor seals, and scaling mr glyphs. The reason why I have AD is because of Leonas ability to auto attack reset resulting in being able to land 3 autos in quick succession in lane. The extra damage really hurts and makes your trades extremely deadly (lvl1 you can take out half of an enemy Jannas hp) Leona was actually originally designed as a top laner, and shes quite good at it too if built tanky AD (Ive beaten fioras and rivens as top leona due to my strong cc and ability to play minion waves to my advantage). Ive heard that jungle leona is possible, but nautilus is in every way better.

if you want to get an S pick her top lane and buy hydra xD

In support it's standard tanky support setup, the only thing you should watch out with leona is WHEN to go in because that may result in your team losing. Even if you use full combo to catch enemies, your combo will be just enough to initiate a fight and after that you are left exposed to die and have no spells to peel for your adc. So for late game you should just use your R to catch enemies and stick near your adc to Q/E unless you are an all in win-win situation

as for lane phase you should stay back and wait for the right moment ( not many minions around ) because whenever leona goes in, she will take minion damage 100%. She proccs her passive very nicely for extra damage with adc's like lucian that hit multiple times in a small amount of seconds. You can as well pick ignite more than exhaus in this meta

Leona has great engage and pretty good disengage. The best I can tell you is make absolute sure you know your team is in a good position to follow up when you engage or you just start feeding and its not fun. Also, leona has 3 CC abilities. Try to maximize that by chaining your cc, meaning don't immediately use all your spells when someone is already stunned. You'll get a feel for that after a while.

Also on a random small note, use your W before you engage because the bonus will be best then. Any initial damage you eat will have to go through the bonus MR and Armor you get, and also the explosion will go off in a more timely manner.

Make sure you pick her with an adc that works well with her. For example, Kogmaw and Leona are NOT a good combination.

Don't be afraid to go too deep sometimes, get used to her limits.

Sunfire is good when you're ahead, but make sure you pay attention to if you should be building locket first.