Warcry
An upcoming specialist game for Age of Sigmar and successor to Skirmish, Warcry is advertised as combining aspects of Warhammer Underworlds and Kill Team, and promises a much more complex and nuanced take on the various factions of Age of Sigmar, presumably by going into detail for small-scale forces that don't have much of a presence in the wider battlefields. Here's hoping for some of the old school Mordheim-flavored combat to be reintroduced into Age of Sigmar!
The Game
Seeking the favor of the Everchosen, warbands of Chaos cultists and other denizens of the Mortal Realms clash for supremacy. More information is allegedly inbound for Age of Sigmar Open Day on July 20th, 2019. The game itself appears to be (at least initially) very Chaos focused, being set in the Allpoints, which is a certain somebody's favourite haunt. There are at least a half-dozen more forces teased by only a single icon for each force. No announcement or other information has been released for any units outside the initial six Chaos warbands below.
Chaos Warbands
Iron Golems
"We Make War!" Hailing from the Realm of Metal, these obnoxiously Norwegian-accented warriors are renowned for the quality of their smithing, believing themselves chosen by Archaon himself to forge arms and armor for the Slaves to Darkness. They also have both Duardin and Ogors.
Untamed Beasts
"Hunt the Hunter!" Bloodthirsty predators (Not that kind, Slaanesh!) from the Realm of Beasts, these primal cultists bring the old school Chaos Marauder vibe with their adornments and weapons made of bone and leather. Of course, what's a good Conan cosplay without rippling muscles, AMIRITE? They appear to be accompanied by a horned lion creature from the bestial realm of Ghur, fully equipped with My Little Pony-ish hip brand.
Splintered Fang
"One Cut, One Kill!" A Chaos murder cult from Cobra Command the Realm of Life, these guys are another multi-race warband, including both humans and aelves, and have a Spartan/Gladiator aesthetic. And snakes. They really like snakes. Like... a lot.
Corvus Cabal
"Pick Clean the Corpse!" A Lost Boys-Go-Metal tribe from the Shadow Realm of Ulgu who worship Chaos in the form of a crow called the Great Gatherer, and as such have a heavy crow theme going on.
The Unmade
"Agony is Our Gift!" A Warband originating in Shyish, the Realm of Death, these Chaos followers revel in both enduring and brandishing physical torment and pain as a weapon. Lots of spikes and chains, even some heavy metal stilts. Can you say Darkest Dungeon?
Cypher Lords
"Let Madness Reign!" Hailing from the Realm of Light, these cultists bring a little more of a civilized and seductive bent to chaos. Their attire is the crisp equivalent of drycleaned Chaos. They are also, interestingly enough, the first insight into what life is like in Hysh, the Realm of Light, since Age of Sigmar began. No Teclis and Tyrion here, folks!
Non-Chaos Warbands
No other information about future expansion warbands has been released apart from the following image. Some, such as the Gloomspite Gitz iconography and the Orruk skull, are easy to identify. Others, however, are not as easily nailed down. Theories about that damn lightning icon!