From MothCraft

Mothbux, denoted with "ℳ", is a form of currency on this server. Its not really attached to anything, however its very influenced by CMI and Luckyblocks. It is designed to work with other plugins as a standard of exchange for items, points, and other stuff like waging bets on minigames like Duels.

To see more about the plugins that use the economy system, check out the link to the category below.