You can read the full notes here, but here's the important stuff:
1. Getting to level 30 now takes half as long
For those unfamiliar, getting an account to level 30 is really where the game starts. You get full use of your rune and mastery pages (which provide key in-game statistics), and you can play on the ranked ladder — it's a key step towards really getting into the game.
Now that process is easier! The total experience required to get to 30 has been reduced by half.
To players who slogged through 400-some games to get to 30: don't be the bitter older sibling mad at your parents for wising up and making things easier for your kid brother/sister. This is a good change and should help new players feel less lost.
2. Changes to Kog'Maw and Soraka
Finding a balance point for Kog'Maw this season has been difficult, as Riot's Scarizard explained in the patch notes:
We're looking to make a sustainable Kog'Maw for the long-term, free from the binary teeter-totter of 'really strong or really weak' that hypercarries tend to fall into. The changelist below represents a shift in thinking about Kog's power curve — he'll still scale incredibly with items, but that curve is now more even across the game (rather than spiking at any one particular point). Smoothing this curve means that Kog's lane can be in a state that's relatively normal compared to his peers, but the 'race against the clock' should feel less harsh for those that fall behind. Kog'Maw may always be the posterchild for what the term ‘hyper-carry' means in League of Legends, but the hope is for that term to extend beyond just ‘bad lane, great late game' and into meaningful interactions between the champions and their environments.
Kog'Maw's attack speed per level is up, and the mana cost of Caustic Spittle (his "Q") is down. Bio-Arcane Barrage (his "W") no longer gives attack speed, but it does have base damage.
Meanwhile, the Soraka changes that have been floating around on the PBE are headed to live. Astral Infusion (her "W") is less powerful and Starcall (her "Q") has a new function that interacts with Astral Infusion.
One note: there's a typo in the Starcall section. Rejuvenation restores 10/13/16/19/22 (+0.1 ability power) health per second.
3. Jungle buffs!
Some old power picks are returning to the jungle and top lane.
Hecarim's Devastating Charge (his "E") regains some of its lost power, moving faster and now knocking back enemies based on how far he has moved. He's been in a pretty weird place in recent patches, due to a combination of pesky bugs and removal of Homeguard Boots from the shop.
Jarvan IV saw cooldown reductions on both Golden Aegis (his "W") and Cataclysm (his ultimate). The biggest change for him is probably the addition of AOE damage to his ultimate, allowing for group assassination potential from the Exemplar of Demacia.
Old favorite Sejuani received a pretty notable buff to her early game, previously the weakest part of her kit. The damage on Permafrost (her "E") has been significantly boosted in the early game, while her auto attack reset on Flail of the Northern Winds (her "W") has a quicker animation.
And while Vi has reliably been a strong ganking jungler, her slow clear time has left her behind when compared with other junglers. That'll be helped by a significant buff to Excessive Force (her "E"), reducing the ability's mana cost and increasing its damage.
4. Nerfs to a pair of AD Assassins
Pantheon and Talon have been a little terrifying to play against recently (and an absolute joy to play with). 6.5 is going to change things a bit.
The damage on Pantheon's Heartseeker Strike (his "E") is down, and while the ability still interacts well with Thunderlord's Decree, this will probably take my pocket Pantheon mid pick out of rotation for a bit. And while Grand Skyfall (his ultimate) costs less mana, it no longer refunds that mana if you cancel it.
Talon's been a very strong mid laner since the addition of Duskblade in 6.3, and a nerf was inevitable to try and slow his snowballing. Shadow Assault (his ultimate) now costs more mana and has a higher cooldown.
5. New champ select sounds
Now you'll know by sound when it's your turn to pick and ban, or when someone is trying to trade with you, or when someone picks or bans your intended champion! What a wonderful world.
League of Legends Patch 6.5 should be live either later today or later this week.