It seems intuitive to have AD supports in the game when there are many AP supports. Well, the thin is AP suppports don't have much going for their auto attacks. That is much more of an excuse than a real argument.
An AA based support is just as much an AD support. Although it is tricky to create a concept that revolves around an AD support, it is not impossible. There are a good number of fighters who can support, especially since Knight's Vow came out. Fighters with massive sustain and mobility, like Xin and Lee Sin, proved viable in my tests. However their kill potential and lack of interaction with their teammates prevents them from becoming viable supports.
Now, to understand supports you have to understand their itemization. Preferably you would want to have them build CDR and mana, health .. It's obvious why. The longer you last in a fight and the lower your cooldowns are you can spam more of your disables. It's not uniform, but it's the most common you will see.
Now following the aforementioned characteristucs of fighters and supports, we can try to build a concept around this.
First of all, the innate ability. Looking at other fighterish supports, that ability has a scaling factor so it's relevant throughout the game, but at a considerable drawback. Braum cannot stun that often, Leona can't trigger the passive herself, Nautilus can't trigger it on the same enemy in a short time ... It doesn't help them as much as much as it benefits their team. This allows them to build stats that greatly benefit thm in other ways, indirectly potentiating the innate ability.
Since we have determined that an AD support wikl be an AA based champion, their passive needs to encourage the utilisation of on-hit damaging types. I would propose in such cases utilisation of crit and attack speed to indirectly enhance potence of such innate.
Innate: Critical strikes deal 150℅ damage. Applies to on-hit damage modifiers. Also, after 4 attacks or damaging abilities the next basic attack is guaranteex go crit.
Now that we have established a core stat, we can itemize and establish the rest of the kit around these base stats: crit, cooldown reduction and/or attackspeed.
How will this allow for a support to be born? By having on-hit implied, we allow for a variety of defensive items to be built. Furthermord, we encouragd inovation, for the rest of the kit has to revolve around utilization of this mechanic and these stats. What I am having in mind is this: heal calculated from total damage dealt.
Q: Nexf attack gains range. Damage enemy for increased damage. If the target is an enemy champion cooldown is refreshed and the next Q will deal ℅ max health damage. This can be refreshed indefinetely, as long enemy champions are hit.
What we are trying to accomplish is get synergy with the innate ability. Thre is not much to be explained here. Build defensive stats, survive and hit enemies indefinetely.
At this point it would be sane to discuss the persona in question. When coming up with this concept I had pictured a bulky warrior/monk wielding a totem-turned-staff. Imagine raising a totem and bringing it down on your enemies over and over and over untill they are dead, you die or you run out of mana.
What we've seen is not very supportish. We have to solve this with the rest of the kit. It's not imperative, but some interraction with ghe rest of your team has to exist.
W (Passive component): Heals on self heal nearby allies for 30-70℅ of the heal. Additionally share shields with surrounding allies. Shield power increased by 20-50℅, the lower your health.
W (Active component): For 6 seconds gain attack speed, increased when fighting alongside a friebdly champion. At the end of the duration heal yourself for ℅ of damage dealt.
The passive component excludes indirect heals and group heals cast by other means (Summoner Heal, Janna Ult, Soraka Ult, Knight's Vow, however casting Summoner Heal or Redemption yourself will heal all champions implied increased by a percentage of health you healed yourself).
Sharing shields means shield can be damaged hitting either champion. Allies gain the shared shield immediately when coming in range and lose the shield when going out of range.
Imagine getting Maw and having it's shield triggered. It's shield would be increased on low health and surrounding allies would also be granted the shield. Bloodthirster would work great aswell.
How many times have you been in 2 v 1 fight as a support only to have your ADC killed by a beefy Maokai, while you stood there helpless a nd powerless? If only you could heal them somehow.
Now, as I mentiones before. The character in question wields a magical totem/staff. It would be stupid not to show some of that magic in one of the basic abilites. What we lack in this kit is some form of crowdcontrol. Now when designing a battle support, we can't go over the top. You either have mobility and shields, or beefiness and CC. A compromise is to have both, coupled in a single ability (Cho'Gath). I propose ghe following.
E: Strike the ground with the staff, emitting a shockwave that slows enemy units in a small cirle. After a few seconds a shockwave is released at the same position that briefly knocks up enemiea in a larger are, exclusing the initial smaller area.
Think of this as Nautilus E; first wave is a slow, the second is a knockup. Both shockwaves deal magic damage, scaling of attack damage (inspired by Lee Sin's Tempest)
Considering everything that we have, we lack a self shield. W implies group shield - without any shield. Inspired by mechanic of totems from Path of Exiles, I came up with this.
R: Place three totems in a triangular shape, after a brief delay the totems form a sacred ground where allies are granted a shield that protects from magic damage. While in the area, the shield is slowly regenerated.
This practically grants immunity to magic damage. Strong burst might deal some damage, but the shield would slowly recharge back. Also, our hero can stay in the area providing the shield for his allies, constantly recharging it for them.
Tell me what you think.