Just like most Fiends and Celestials, Mammon was supposed to take a long time to recover from his injuries.
However, he had a special power that allowed him to "pay" to heal his injuries instantly.
Unfortunately, the price tag to be as good as new was ten billion gold coins. The greedy Fiend felt his heart break as he let go of his money to recover from his injuries.
This amount of money was equivalent to a fifth of his overall wealth, making him feel very angry and frustrated.
After his recovery, the first thing he did was to attempt reclaiming the Divine Keys before rethinking his strategy.
But he made one mistake.
Once the keys were used, they couldn't be retrieved unless all seven keys had unlocked all the gates protecting the castle.
This discovery made Mammon scratch his bald, golden head in frustration. He wanted to leave but couldn't. If Zion arrived with the Key of Pride, wouldn't that mean that all of his hard work would fall into the hands of someone else?
