https://www.pcgamer.com/destiny-2s-crimson-days-event-includes-a-new-map-and-2v2-clash-combat/

Destiny 2's Crimson Days event, confirmed for a comeback in January, will feature a new map called Burnout, the studio revealed today, and a new 2v2 Clash mode that will very strongly encourage players to stick together. Abilities will recharge faster for partners in close proximity, while those who stray too far apart will be marked by waypoints telling their enemies where they are. 

Crimson Days will offer the usual array of themed rewards, including ornaments, emotes, ghost shells, sparrows, and shaders. Most of them will drop from Crimson Engrams, with a "knock-out list" ensuring duplicates won't appear unless and until you earn everything. Crimson Engrams are earned by playing the Crimson Days Crucible playlist and will also be awarded along with Bright Engrams at level-up, and there's no cap or limit on them.