The London Mulligan was tested at Mythic Championship London in early 2019, where it received overwhelmingly positive reception from both players and coverage teams
The Attrition Engine: Using card-draw engines like Greater Good and recursion via Conduit of Worlds , the deck can recover from board wipes effortlessly, out-valuing opponents in the late game
Currently, this card is used to get out of Special Conditions like sleep and poison and is a fairly effective counter to the Hypnotoxic Laser/Virbank City Gym combo that is so prominent in the game right now
Sure, the abilities are similar, but Thassas Oracle allows you to have at least a few cards in your library for its instant-win scenario, whereas the Maniac leaves you completely denuded of anything in your library
Developers reportedly didnt even want to release the set, and the poor communication between design and development came to a head more severely than it likely ever had before