Ofc I have the typical ones: remove k’sante, yuumi, but lets jump to the other ones.

Gnar rework
Make Garen E stopabble
Make Tahm’s a Silence/Stun
Make Syndra and Yas R stop on death
Make Illaoi tentacle smash stop on death
Give Illaoi R tentacle hitbox
Remove on-hit from Irelia Q
Nerf Botrk
Remove damage reduction from Briar, Yi, Bel’veth and Irelia
Make all turrets damagable at all times, but they always get 0 damage until the outer one gets destroyed
Turrets deal %hp damage, and ignore armor (or at least the Nexus ones)
Fix Yone R hitbox
Remove Sheen from Iceborn
Nerf Liandry’s
Rework all Liandry’s dependent champs
Heavy changes to botlane, to banish fake support
Make Vel’koz, Brand, Heimer, Lux, Xerath a proper midlaner, and remove all chances to play them at botlane
Reduce Senna base range, and give her stacks a cap
Make empowered Camille Q magic damage
Remove Corki E
Nerf Lux scalings, increase her ultimate CD, and make it go to cd, if she dies while casting it
Increase the CD of Q in the early and mid game for the Airborne Trio (Yas, Yone, K’sante)
Remove Yasuo’s R “helper”, that won’t let you go into turret range
Remove Lethality Sion
Remove Hearthsteel or rework Titanic Hydra and Demonic
Remove Jax E
Give Morde Passive 4 or 5 stacks instead of 3
Zyra vfx
Do something with Predator and Unsealed Spellbook or replace them
Give Kat an identity finally
Remove Static
Either revert the oracle changes or give Teemo Shrooms 2 hp instead of 3
Either make a new ward, that is effective againts invisible things, or make an item for that
MR antiheal
Make a proper AP anti shield item, and make MR and Armor anti-shield items, and give more champs anti–shield /anti-heal
Remove slow from Gp barrels, and nerf armor shred, or remove the Sheen effect with it
Nerf the Teemo Shroom slow
Give Pyke something to be viable in late game
Either nerf Thormail, or Rammus, or rework Rammus
Make Vayne W deal magic damage, with increased %hp ratio
Rework Trynda
Stop making new champs, and fix the current ones
Remove Vi R
Make Wukong’s R stoppable if cc-d
Rework ranked system, remove MMR, Remove Emerald: Make a “Fix” LP gain/lose, and it gives you more or less according to your overall performance. Performance criterion must be made for each role individually (or atleast make main roles, supp, and jg a different one). If someone leaves it makes you lose less Lp and gain more.
Make stricter ranked penaltys
Implement ranked only bans, so you wont be able to play ranked for x time( hrs to days or max weeks)
Increase Ranked requirements to atleast level 50
Remove Hullbreaker
Make Rotating gamemodes rotating, monthly change in gamemodes
Nerf/Rework Rengar W and R
Make Jhin W more visible
Remove Ability Haste
Revert the Attack range increase from Lethal Tempo
Bring back adaptive helm
Make runes more detailed ingame
Make post match analyse more detailed including runes
Practice tool where multiple players can join, and there would be a host who can give the permission to other players, to test things together, and make it easier.

Thanks for reading this long Christmas wishlist!