by all thats periphery

When he first comes up with the idea, he thinks it’s ludicrous. He’s finally gone mad from the stress.But the longer Mumbo toys with the idea, the more he thinks it could actually work. Because maybe he’s never met Grian face to face, but he knows the man. He knows how his mind works. The thief is prideful. He sees the words “most secure vault in the world” and sees it as a dare. Grian is relentless until he’s succeeded, even if it risks his safety. Most of the man’s close calls have been in smug gimmicks mocking the authorities. If Grian wants to provoke him so badly, then Mumbo can play the thief’s game and win at it.“You see, Grian loves a challenge, so let’s appear to give him what he wants. A challenge, but a decoy challenge.”  He's going to make a decoy vault for the thief to break into.//or, Mumbo and Grian’s vault warfare from season 9 dramatized to the furthest extent