War of Omens has 4 distinct factions with different gameplay. Vespitole, the Daramek and Metris were available at launch, while the Endazu were added in a later patch. Each faction has it's own unique set of available cards
The Vespitole are a vast empire of merchants, warriors, tradesmen, aristocrats and mystics that seek to control all of Ausonia.
They have two different main mechanics; controlling an army of various allies, and using instant card effects.
The Daramek hit hard and rely on animal sacrifices to fuel their actions. The Daramek may seem weak at first, marshaling multiple, low-impact minions like rats, pigs and goats, but rather than use these minions for offence, the Daramek wait for their destruction, using their deaths to fuel much more powerful cards.
The Metris is the remnant of an ancient society, now all but extinct. Their homeland is destroyed and forgotten, making knowledge of their ancestry the Metris' most coveted secret.
Mechanically, they are mostly about using one-shot effects (almost all of their cards are destroyed upon use) that hurt their foes either directly or indirectly.
The Endazu is a legendary congregation of adept magi built on foundations of arcane magic. This autonomous group of mystical individuals, rooted into the history of Ausonia, resides in an ancient palatial city among the desert mountains of south Dalmiria. It is from them that age-long myths of terror and mystery originate.
Mechanically, they are about generating magic, charging up cards by keeping them in hand, and using magic to fuel effects.