TL:DR
- Illaoi is playable in the early game.
- Xayah is a better item holder.
- Space Jam may be playable.
- Cassiopeia does a little less damage.
- Mech Infil may be playable.
- Jeweled Gauntlet isn't shit.
- Zz'Rot portal is more playable in stall comps like Mystics Vanguard and Snipers.
- Six BM is dead.
Game Changing
- You can no longer duo or trio queue in Master and above. RIP scrims.
- A new Galaxy, Binary Star, has been released. You can only equip two items in this Galaxy.
- Medium Legends has been removed @DummyThic.
- Illaoi has 7.7 percent more health, ults for 50 percent longer and steals 50, 33.3 and 20 percent more stats at levels one, two and three. This should make you a lot happier to see an Illaoi pair.
Major
- The minimum number of items that can be dropped has been raised by one. This will reduce RNG and allow players to climb more efficiently.
- Battlecast damage and healing has been increased by 14.3, 12.5, 47.7 and 46.7 percent at two, four, six and eight. This'll be nice when splashing two Battlecasts, but it probably won't be enough to run six Battlecasts.
- Xayah requires 14.3 percent less mana, or one less auto, to ult. This should reinstate her as one of the best early-game item holders.
- Darius has 14.3 percent more armor, 50 percent more magic resistance, and deals 10 and 6.7 percent more ultimate damage at levels two and three. Space Jam anyone?
- Kog'Maw has 10 percent more health, requires 25 percent less mana or one less auto to ult and does 14.3 percent more ult damage at level three.
- Cassiopeia's ultimate lasts 16.7 percent longer, essentially meaning she does 16.7 percent less damage.
Fizz requires 16.7 percent less mana to ult. This really makes me think Mech Infil could be back.Correction: Fizz requires 16.7 percent MORE mana to ult.- Gnar's ultimate stuns for 25 percent less time.
- Jinx gets 16.7 and 6.7 percent less attack speed from ult at levels one and two. You'll have to streak just a bit harder to win with Brawler Blaster or Rebels.
- Jeweled Gauntlet gives 50 percent more crit damage. Now you're not as sad when forced to build it.
- Zz'Rot Portal's minion has 50 and 12.5 percent more health at levels one and two. This makes it a great item in comps that want to stall like Mystic Vanguard and Snipers.
Minor
- Six Blademasters proc 7.1 percent less frequently. This kills the six BM comp which barely had any firsts to begin with.
- Four Blasters hit 20 percent more targets. This won't stop Jinx, Ezreal from being optimal.
- Six Cybernetics grant 6.3 percent less AD and AP. With other nerfs, Cyber Vayne will still be the best comp as she's been untouched.
- Dark Star gives 12.5, 16.7 and 18.8 percent more AD and AP at four, six and eight. This will not put the comp over the edge as no one even runs two Dark Star, let alone four to six.
- Four Infiltrator grants 14.3 percent more attack speed. This may bring Mech Infil back, but Mech Sorc is probably still better.
- Nocturne has 7.1 percent more attack speed. Neat.
- Nautilus requires 16.7 percent more mana to ult and stuns for 14.3 percent less time. He's still one of the best units in the game; don't worry about it.
- Jayce has 5.9 percent less health. Fair enough nerf.
- Riven does 10 and 6.3 percent less ultimate damage at levels one and two. I've never seen Riven successfully played, so nice meme?
- Ekko's ultimate does 25 percent less damage at level two. Good nerf.
- Thresh requires 20 percent, or one more auto, to ultimate. Great nerf!
- Statikk Shiv does 12.5 percent more damage. Neat.
Insignificant
- Four Mystic grants four percent less magic resistance. Nice meme.
- Bard casts his ult faster. Extraordinary meme.
- Master Yi does 12.5 percent less ultimate damage at level three. Six BM was already dead.
- Teemo's slow lasts for 25 percent less time. The memes keep coming.
- Bloodthirser and Gunblade heal for 12.5 percent more. Gunblade is close to being good, but Bloodthirster should probably just be removed.
Compositions
I'm not going to give a description for any of these comps as I've literally only played one game on Set 3.5 and took 8th. Please take positioning and itemization with a grain of salt.
Also, the meta should pretty much stay the same other than Space Jam and Mech Infil potentially being playable. They mostly just changed how the early and mid game play.