Champion concept: Nekrates, the cursed life threat
Concept: This champion came to my mind after thinking in 2 things, both related to our beloved 
First, i was thinking about old pre-rework Yorick. Yes, that champion was pure garbage in all senses, huh? probably the most booring, toxic and senseless champion ever in the game´s history... but lets give him something. His old ult was VERY INTERESTING. If you dont know what it did, go check for the game´s wiki, in the history section on Yorick´s page. Youll sure find it impressive.
Second, the fact Yorick is a juggernaut necromancer who is based in splitpush, creating an army of ghouls that slowly eat the map and 1v1 duels makes him unique, but how about a necromancer who is really designed for teamfights?
So i conbined those two ideas in some free time to design this champion.
About his aspect and stetic, i was thinking something similar to the necromorphs from Dead space saga. The own Nekrates has human form but its easy to see he is constantly mutating behind his flesh.
Type of champion: bruiser, juggernaut.
Lets go.
Lore: Nekrates was born with an ability that only one person every various hundred years posseses; the power to bring back to life dead things. But im not talking about poor necromancy, zombies reanimated just for some time, dependant of their summoner. He was also able to do that too, but his true power was to REALLY revive dead people with no secondary effects, like they never died. Nekrates was, in fact, a primal necromancer, the first and most pure form of the magic of the afterlife, wich allows the user to trully control the line between the life and dead. Sure the ruined king would have liked to meet him. At the beggining, he had a lot of respect for this own power. He though the rules of life and dead should not be broken. Only used this ability to help those who lost their beloved ones in tragic ways. But time passed by and he slowly changed his mentallity. Some people could say he became a worse person, but in his eyes he just grew stronger. He began to abuse his ability to force powerfull warriors and mages to give him their secrets in exange of recovering their fallen friends and family. With time he became an extremely strong necromancer, with his unique form of magic wich mutates flesh into monstruous creatures that only he can find beautifull. He also began to use his magic on his own body, making himself something similar to a human, but clearly differrent in the insides. His ambition finally reached its climax when he heard about a powerfull items with the form of runes, protected by an arcane blue mage and their enormous power able to even change Runeterra inself. A new frontier of oportunities opened for him. What if he could absorb that power and make his own abilities stronger? What if he could bring down the whole world to his knees? Nekrates´ ambition is now to absorb the whole world by using his power multiplied by the energy of the runes. He wants to turn the entire planet into a single living organism under his command, and use it to travel around the universe consuming more and more worlds... until he is considered to be the biggest god of all existence.
Note that the names of the abilities are names of heavy metal songs, a little tribute to 
Passive: LET THE BODIES HIT THE FLOOR. -Nekrates pressence in mid-large distance makes enemies who die leave corpses behind for a max of 10 seconds. Nerkates can walk near a corpse to absorb it, restoring hp and mana. Minions and little monsters leave little corpses while canon minions, champions and large/epic monsters leave big corpses. Absorb little corpse: restores 0,25% max hp. Absorb big corpse: restores 5% max hp and 5% max mana.
Q: SICK FLICK. Cost: 30/35/40/45/50 mana. CD: 8/7/6/5/4 seconds. Nekrates makes some tentacles appear on his arm and hits the ground with them jumping so he dashes a little distance to the chosen location (cant pass walls). This creates a little explosion witch deals in area 40/60/80/100/120 + 80% total AD physical damage and slows enemies down a 50% for 2 seconds. If at least one enemy champion is affected, Nekrates heals a 5% of his max hp.
W: SECRETS OF THE DEAD. No cost. CD: 20/19/18/17/16 seconds for charge (affected by cdr) Passive: Nekrates can right click on a corpse in any distance from him to concentrate during 1,5 seconds (he can move and use abilities while he does) and then absorb it from far distance. This effect has a cd of 10 seconds (the cd doesnt affect the active of this ability)
Active: summons from 1 to 5, depending of the number of charges, mutated zombies who fight will alongside with him. The zombies have a 50% of Nekrates hp and a 25% of his total AD. The charges can be reloaded faster by getting corpses; absorbing a little corpse reduces 25% time of wait to a stack. Absorbing a big corpse instantly grants a stack. Their autoattacks deal damage in area near them and gives stacks of blood omen to enemies affected for some seconds, max of 10 stacks. Every stack makes Nekrates and his pets to deal 2,5% more damage to the affected objetives and also reduces a 1,5% the damage the marked objetives deal to Nekrates and his pets. If the zombies get too far from Nekrates, they bury themselves for a bit seconds (can be attacked while they do that) and appear near him.
E: OUR FINEST HOUR. Cost: 80 mana. CD: 20/18/16/14/12 seconds. Nekrates summons a bloody tentacle in a short-mid distance wich after a little delay explodes and deals in area 10/25/40/55/70 + 80% total AD magic damage and stuns near objetives for 0,2 seconds. If zombies are up, they are instantly absorbed by the tentacle and its damage and stun duration are upgraded a 20% for every zombie absorbed (max 140 + 160% AD and 1 second stun) After that, the zombies quickly reform near the zone and get** furious**, so they priorize their attacks on enemy champions, are ghosted and gain an attack speed and movement speed bonus for 6 seconds.
R: PAIN REDEFINED. Cost: 100 mana. CD: 160/140/120 seconds. Nekrates creates a controllable blood copy of himself or an ally champion for 10 seconds. The copy has the aspect of the objetive in red, but its stats are independent and cant be buffed or reduced by other effects. Stats: same movement speed as Nekrates, 80/100/120 armor and mr, 80%/100%/120% max hp from Nekrates and 80%/110%/140% of his total AD. 0.80/1/1.20 Attack speed. It deals 30% less damage if its ranged. If the objetive dies while the copy is active, he resurrects instantly in the copy location with a 50/65/80% of his max hp. After resurrecting and before being independent again, the champion is in "vinculated" status for 10 seconds, wich reduces a 40% the shields and durations he gets by any source until the time expires. If Nekrates dies during the vinculated status time, the resurrected champ also dies instantly.
Pets: https://imgur.com/a/TxNUMup
Notes: -Mutated zombies deal 50% less damage to towers and tower hits hurt them for a 50% of their max hp. Also they are priorized by the tower before little minions (not canons) -Unlike Yoricks ghouls, the mutated zombies dont die by one single objetive attacks, but are harder to prepare to summon and cant push away from the champion. -The blood copy dies instantly if Nekrates dies before the copied champ is killed. -If a resurrected champ survives for more than 10 seconds and Nekrates does it too, the vinculated state disapears and the champ is alive and non-dependant again. -The blood copy cant be healed by any source. -Pain redefined can be used on Nekrates but thats way a waste in tfs. -The corpses spawn distance is like 50% more of Yoricks aura to make tombs appear and disapear when he goes away. -Mutated zombies cant be healed except in base´s fount. -Secrets of the dead can be used to summon zombies in any moment with stacks, even with less than 5 zombies active. Once you have 5 zombies, using the ability will kill the ones with more damage taken to raise others with full hp.