Paladin champ with a mace that turns into a flail glowing with divine powers with his skills.
AP Bruiser without mobility but with the CC of a tank and DMG of a bruiser.
Passive could be like that rune that heals allies when they hit CC'd champs healing allies for 10% of Paladin AP and healing the Paladin for 20% of his AP. (works with abilities but only 1 heal with DoT effects)
His/her Q (I think he should be a male cuz we already got Leona) must be a linear attack with the flail that passes through minions damaging them and stopping at the first enemy champion hit damaging and briefly slowing it(medium damage and low CD, good scaling but low base dmg).
W a shield bash that works like Olaf E, stuns for 1.5-2 sec, long CD and good base and AP damage, gives a big shield to the paladin that increases with his currenthp% but only lasts 2 sec.
E got a passive and an active, both scale with E rank:
Passive is a buff to Aa that gives magic damage, giving them a small AP scaling with some base damage too (10%/12/15/18/20% AP 10/15/20/30/40 base dmg) this damage increases by 50/60/75/90/100% when the enemy is CCed.
Active, the Paladin swings its flail in a frontal arc, this attacks knocsback enemies and then stuns them for 0.75 s, deals 70-110% AP and 2 per 100 AP-5 per 100 AP %maxhp damage, it doesn't have any base damage. the CD is a bit long.
R: A Buff to everything on the Paladins ki turns his mace into a glowing flail for the duration increasing Aa range to 350, increases by 50/75/100% the power of Passive and E passive, adds a bonus damage to skills of 20/30/40% AP and increases the duration of CC and shields by 1 second. 10 sec duration.
He is forced into the bruiser build becaude he doesn't have the base damage to be a tank, lacks the mobility and fast animations of an assasin and doesn't have the range of a mage.
His Q should be maxed against ranged champs or strong lane bullies to farm and poke from a safe range, W is worth maxing when you will be doing long trades in melee range.
When the R is active the Paladin should be able to duel any melee in the game and any ranged that gets into the Paladin melee range. It gives a lot of CC and heavily buffs his dps, both passives benefit from the R buff and the increased CC duration and the extra Aa range allows him to attack right after his E and anyone who uses a small dash to get escape.