Riot Games designers shared a final 12.13 patch notes. Corki and Volibear are getting nerfed, while 11 champions will get buffs of different sizes. Comeback mechanic in objective bounties also will end up significantly weaker.
The main change of this patch is the addition of a new champion Nilah. You can read all about her on our site.
Besides champion changes, Riot Games worked on objective bounties. They tried to change the way a team who are behind just a little is able to get multiple bonuses and gain a significant lead. Now getting one objective bounty will cancel all other bounties, and there are other changes, reducing their impact.