Hello! I just want to say, I really love this concept! I've always wanted to see a voodoo themed champion and this is beautiful. I'm also a support main, and I'd love to see a champion with a kit that revolves around "possession". Anyways, since you asked for suggestions and this really intrigued me, here they are:
- Expand upon his design.
I'll be honest: I really freaking love his design. However, it doesn't really fit League. Perhaps make him a bit more "voodoo-y". It could go a million different directions, but a suggestion I'd have would be to give him some sort of mask.
- Expand upon his lore.
I know this must be a work in progress, but his lore isn't very clear. It mentions a king- who is he? How did Boko end up in the Shadow Isles? What is his motivation? What is his personality? This is important because it could affect his design/abilities.
- Make a more cohesive skillset.
"Linking" champions is a really cool idea that has a lot of potential. But he can link to both an ally and enemy at once? I think it could get a bit confusing especially due to the damage sharing. Plus, the passive just seems like a glorious Kog'Maw passive. It would be cool if he revolved around "linking/tethering/possession" a bit more.
I also thought for a while and imagined how I think he could be improved. These are just some random ideas I had, and it's a bit too convoluted but I understand if you think this doesn't represent Boko. But you can use this how you wish, just something that might give you inspiration. :)
{Passive} Voodoo -- Genius name I know!
Boko gains stacks of Voodoo (max. 10) depending on how long he has been linked to someone else. These stacks decrease the damage taken by Boko by (X%) per stack and increase his damage (X%) per stack. Stacks of Voodoo gradually disappear if not linked to a champion. (Voodoo stacks take the appearance of pins on Boko's body)
{Skill 1} Q: Ghostly Ties -- (Targeted Ability)
Boko links his soul with another champion. The ties are broken if Boko or the target are out of range or if one of them die.
Ally cast: Boko redirects 12%/15%/18%/21%/24% of damage taken by his ally to him. Additionally, Boko and his ally gain increased regeneration and movement speed for a short time if the ties are broken.
Enemy cast: Boko redirects 12%/15%/18%/21%/24% of damage he takes to his enemy. Additionally, Boko and his enemy gain increased regeneration and movement speed for a short duration if the ties are broken.
{Skill 2} W: Ectoplasma -- Instant Cast
Boko sends magical energy through his link with a champion. The projectile speed is increased depending on the number of Voodoo stacks, and it consumes all stacks. This ability fails if the target is not linked anymore.
Ally cast: Boko sends a healing pulse, that travels through the link into his ally. This pulse heals them for 8%/9%/10%/11%/12% of their missing health and heals Boko for half that amount.
_Enemy cast: _ Boko sends a dark pulse of energy that travels through the link to his enemy. This pulse damages them for (X) amount and slows them for 99% for 1.5 seconds.
{Skill 3} E: Tether Together -- 2.5 second Channel
Boko channels dark energy and brings his linked champion and himself closer together (both are moved- think Nautilus hook). The duration of the channel is lowered by 6% for each stack of Voodoo. Boko's channel can be interrupted and stopped if he takes damage from an enemy champion (but not damage from his ghostly ties).
{Skill 4} R: Possesion -- Instant Cast with 1.5 second channel
Boko takes an ethereal form and possesses the champion he is linked to. The duration of this skill increases with the number of Voodoo stacks (.2 seconds per stack), and consumes all stacks.
Ally cast: Boko possesses his ally for 5 seconds, granting them 25%/35%/45% of Boko's bonus Armor, Magic Resist, Health, Attack Damage, Ability Power, and Movement Speed. At the end of the possession, nearby enemies are feared for 1 second. During this time, Boko cannot cast abilities or move but may recast to end his possession early. Boko is returned to his location at the time of the cast.
Enemy cast: Boko possesses his enemy, suppressing them but able to control their movement for 2 seconds. During this possession, the enemy takes 8%/16%/24% increased damage. At the end of the possesion, nearby enemies are feared for 1 second. Boko cannot cast abilities or move while possessing, but can recast to end his possesion early. Boko is returned to his location at the time of the cast.
Quite a large wall of text. I'm sorry if that was too long to read. :P But again, just some ideas I had while reading this. I wish you good luck on Boko and I'm with you wishing he's a reality someday!