From Postums on Waypoint:

Hello Halo Wars Community,

Season 12 is upon us! Thursday of this week we are planning on updating Halo Wars 2 to the newest season as well as adjusting matchmaking rules for all 3 of the ranked deathmatch playlists. We are working on the next balance update, but this will not be coming until sometime early next year.

Ranked Deathmatch Changes
The changes to Ranked Deathmatch include a new set of matchmaking rules that is much stricter on skill level matching. With this change, you likely will see increased search times especially at the lowest and highest levels of rank. This is a change that has been requested by the community for quite some time and we are going to let the community give us feedback on how the rules feel once updated. These changes to matchmaking rules will apply only to Ranked deathmatch for 1 vs 1, 2 vs 2, and 3 vs 3 for now. We will be monitoring the health of these playlists after these changes are implemented to see if they need to be loosened or tightened even further.

Season Update
Season 11 was a fun one for many. During the season there were several balance updates that were shaped by members of the community that are a part of our Halo Wars Private Test Realm. A huge shoutout to these members who have been helping us to shape balance updates for the past several months working in conjunction with Wrensi.

We would like to offer a heartfelt thank you to ASolidConviction, BreezyStarfish1, BtC Slick, CarsandCamera, EdPeter, Flame Pieman, Hosticide, LargoPancake40, metaloidmonkey, mightyhoax, MikeBeastON, TPietro76, Vexed, Viper Skills, xandy92, and Yodesla. Your help and contributions have helped in the shaping of Halo Wars 2 and where it is today. Thank you!

As always, please use the forums here for leaving feedback, telling us what you would like to see next season, any balance concerns you have, or to have discussions around Halo Wars. We look forward to hearing what you have to say!