List of champion design ideas

A ghost champion who can freely walk through terrain and units (can't leave the map). Would have powers like 10 second duration stealth but you can't attack or cast spells while stealthed and you have no way of breaking it other than waiting for it to time out. When your stealth times out you would fear anyone in a close range due to the jump scare. Your base model would be some generic ghostly thing, but everytime you get a kill or assist your model would change into a ghostly version of the champion that died and you would get some sort of bonus (to fear duration?) when you use your abilities on the champion you are currently already the ghost of.

A parasite champion who can attach to an ally or enemy to take control of them for a short time, breaking any cc on them when he jumps in and replacing his own spells and items with that champions so he can really control them in a much deeper way than 'pets' like mord ghost that can only autoattack.

A champion whose skills revolve around the turrets in game, allowing him to do things like repair them, upgrade them, fix a destroyed one (maybe as an ultimate?), temporarily take control of or disable an enemy turret, freely create a permanent turret structure at a location (like azirs turret except anywhere and it doesn't decay over time, limit 1 out at a time)...

A true sniper champion who had stuff like, standing still for 10 seconds is required to use q which is a global single target skillshot with damage that increases over distance (doing nothing at close range and hitting the normal damage basic spells have at 1000 range, and increasing beyond that up to a cap), the ability to mark a target champion or location and keep semi global range vision on it as long as they are in range, tripwire traps to place around the map that don't do damage or give vision or cc, but which trigger and make a noise on the snipers minimap to let them know an enemy walked through there (the power budget taken from cc and damage and vision would go towards making the traps long duration, having many out at a time, cheap or free mana cost, dropping them from a safe range, etc.). The kind of sniper who operates strategically and tactically to create advantages for the team, but who can't do shit in a fight if you get within half a screen of her mid-lategame and who doesn't scale with crit or attack sped at all (maybe an ap champion?) and has no escapes if you manage to get the jump on her despite all of her scouting abilities.

A sword and shield using traditional knight champion who is designed to be a toplane or jungle fighter, not a tank.

A champion like Scyther (yes the pokemon).

A detective champion who gathers clues and evidence during the game that can be cashed in to select a champion and make them into a villain, giving the detective bonus effects against that champion. Would have special mechanical and voice over interactions with garen and cait/vi.

A sorcerer champion who has to go around performing rituals at the location where enemies/allies have recently died or where big/epic monsters died in order to power up and customize their spells. The game would keep track of how many of each type of ritual has been done so far and alter the sorcerers spells. if they have so far mostly performed the ritual over dead allies, their custom spell would be some sort of healing or protective spell to protect their allies, if they had mostly done a ritual over dead enemies they would instead have an offensive combat spell, if they had done it mostly over jungle/epic monsters they would have something like a powerful smite for controlling objectives, or if they maintain a perfect balance between rituals than the spell is something stronger and more valuable than all three. Maybe the custom spell is the ultimate, which would allow it to be truly powerful and versatile. The other two basic spells would probably exist to fill out weaknesses or make them viable in lane, like a waveclear spell and an escape or something, but both would still have to do with preparing before hand like drawing a magic circle on the ground next to the turret that armed after 3 seconds and could then be instantly jumped to within a certain range and a powerful long range wave clear spell that had a 5 second channel time before it launched, making it shitty for harass but great for waveclear and devastating in a teamfight if your team supports you and sets it up so you don't die while channeling (maybe sion style where you can release early for a proportional fraction of the effect, with the accompanying ground target visible to the enemy team).

An illusion champion who's ultimate works karma style to empower their spells on an ammo system. A non empowered spell is an illusion and has no effect other than audio and visual effects, and an empowered spell is real and does damage and have effects like a normal spell. The illusion and real version of a spell have separate cooldown so you can cast the spell twice rapidly with one being real and one being fake. There would be ways that you could more easily tell which spells are illusions, but in general it would be difficult enough that it would become a mind game rather than a reflex game.

A computer hacker champion who can do all sorts of utility things like temporarily cause the enemy team's HUD to vanish or cause their screen to be rotated for a few seconds - effectively working like a stun or a something except you can still act if you can manage to work through the distractions.

A martial artist champion who used melee skillshots like riven, fiora, sion, darius to use their punches and kicks - ideally being designed to not be strong early and fall of late like leesin and without any sort of magic powers, just skill and fitness.

A pimp style champion who can't fight very well, but who gains gold and xp very fast and can give that gold and xp to allied female champions. Also gives a status buff aura to nearby female champions. Takes extra damage from caitlin and vi. <------ this ones a joke to see if you're still reading

An assassin who uses a pistol, who is designed not to be able to adc (perhaps they have a low base attack speed and purchasing attack speed has a different effect for them similar to how crit has a different effect on ashe). Preferably a jungler because an assassin isn't supposed to be chilling in lane with someone, they're supposed to study their targets patterns and then come out of the shadows and kill them and leave. Maybe similar to garens villain or kindreds death mark mechanic, there can be a semi random bounty placed on an enemy champion that the assassin can cash in on by getting a kill or assist on them. This assassin would be great at killing a single target if they could predict their movements (a trap that greatly amplifies damage dealt for a one second?) but have to run if their predictions fail or it becomes a duel since they would be bad without the element of surprise (maybe a long arming time on the trap?).

A tonberry style champion who dealt karmic damage to people based on for example how many kills or cs they have gained since the last time you used your ability on them. This would lead to an interesting situation where you would be super effective against fed enemies but weaker vs weaker enemies (like how veigar scales off of enemy ap, except in this case you would cash in on that advantage once and it would rest unlike veigar who holds your ap over you forever). You would also have to consider whether its worth it at any time to cash in on someone since it would rest your damage on them when you might need that damage for a more important fight or objective later (dont cash in on the enemy adc at a dragon fight when theres a baron up soon).

A soccer champion who has a soccer ball they have to kick around all game (like orianna's ball, but not tethered) to make sue of their kit. Ultimate raises a soccer goal some distance away facing you, and kicking the ball into the goal causes a huge 'GOOOOOOAAAAAL' announcement and provides some huge teamfight utility that incentivizes the enemy team to try and body block your soccer ball from making it in.

A dungeon master style champion who creates neutral monsters that stand guard over an area indefinitely and then, after 5 seconds or so of arming, attack anyone who comes near granting gold, xp, and buffs to whoever kills them. The dungeon master can make any neutral monster, his own or a natural one, weaker or stronger and gold/xp/buff duration will increase or decrease correspondingly. They would be able to purchase monsters in the shop to select which monsters they could spawn (you wouldn't be able to have all options available at once). Their ultimate would allow them to turn one non epic monster into a pet (with a cap on how many), and these would be the only real way they have to defend themselves. They could plant monsters in the enemy jungle to mess with them or plant them in their own jungle for their team to farm. They could splitpush after building a mini dungeon in the forest for people to fight through if they want to catch him.