Mammon is the first demon general you fight, the general of greed. She is perhaps one of the most threatening demon general.
She has a contract with Arwin and is thus situated in Trademond, due to this Mammon has two main major(confirmed) effects on the world.
Mammon is a Major threat as the only demon general who you have to fight at max power, they also are the only Demon general to use a full contract although Belphegor tries, also as stated above it is possible that she is the reason Roland, Claire, Gabriel, and Lysander are under Richards control
In the vice ending of Demon-cracy ‘The Shadow’ reveals the identity of Mammon to be Liliana's mom.