Most of the mid-season stuff should be on the PBE within the next day or two. As usual it should be pretty easy to identify most of the changes, there are a few things I wanted to call out though since they may not be as easy to spot as the more standard stuff like champion adjustments. Some of this stuff will also be discussed in more detail over the next few days by the developers working specifically on it too.
* Jungling XP's getting adjusted. In particular Machete now gives more XP, including the catch up XP if you're lower level than the monsters themselves. That's a change targeted primarily at how safe and effective buddy jungling is in organized play.
* Tower damage will now ramp up quicker against champions and will maintain it's ramped state when swapping between multiple champions. Agro juggling during a dive should still be a good play some of the time, but riskier at low levels in particular.
* Death timers will be getting reduced somewhat, probably between the 20-30 minute marks primarily. This is a follow up to the 6.7 changes that targeted 30 minute+ death timers, similarly aimed at reducing how punishing one fight can be and keeping a bit less gray screen time.
* Boot enchants are getting removed. After making Homeguard a universal effect post 20 minutes we wanted to see how the boot enchant system played out. One of the main consequences has been Alacrity on a lot of champions, which as lead to noticeably higher average movement speeds. That throws off balance on a number of things, skillshots and ground targeted AOEs in particular, so we'd like to get average speeds back to a more appropriate spot. Removing boot enchants, now that the most impactful and significant is always provided, was one of the best ways we identified to do that.
* Baron buff duration's going up a bit, in part to draw clear distinctions between it and the Elder Dragon buff (Elder dragon's around half the length, and on a longer respawn timer than normal dragons, so there shouldn't be too many cases of each team taking one of the two and then the game stalling until both are gone).