You can read the full notes here, but here's the important stuff:
1. Tank Ekko has been mercifully nerfed
With a ludicrous 57.7% win rate in the top lane and a presence in almost every professional game, it was clear Ekko needed some fine tuning. Thankfully, Riot has nerfed the base damage on Parallel Convergence (his "W") and Phase Dive (his "E"), attempting once again to shift him more towards AP builds rather than tanky ones.
Also nerfed in this patch: Iceborn Gauntlet's damage and Grasp of the Undying's health steal. Those had been the most popular item and keystone mastery for tanks, to the point that basically any champion could use that combination (along with Sunfire Cape and Spirit Visage) and be successful.
2. Taric's rework will be live
His new kit looks pretty freaking strong -- if you haven't checked it out yet, here's the champion spotlight video.
3. Buffs to Rumble and Olaf
Galio and Miss Fortune also received buffs, but Rumble and Olaf appear to be the bigger benefactors. Flamespitter (Rumble's "Q") now does full damage to minions, rather than half, and the cooldown on The Equalizer (his ultimate) has been reduced by 10 seconds across the board.
Olaf, who already benefitted from the changes to Warlord's Bloodlust but still hasn't seen much action in either the top lane or the jungle, now has increased lifesteal on Vicious Strikes (his "W"), especially in the early game. The passive armor and magic resist on Ragnarok (his ultimate) have been increased by 10, as well.
4. Ranked stats are back in client!
Hooray! You should now be able to click on "see more stats" to see your ranked stats this season without going to a third party site.
5. Infernal Diana! And a bunch of new splash arts.
How cool is this? So cool.
League of Legends Patch 6.8 should be live either later today or later this week.