Ally (3)

Although Billy wasn't making much progress with Mana Shield, he was starting to understand mana better, and he also was training other monsters to send to other dungeons. Since they couldn't be seen or noticed, they needed some special stealth skills like invisibility. Flash wouldn't work since it only was useful on plain terrains. It was possible for his monsters to have such skills, but the mana consumption was high, so they would need some extra time developing that. It was kind of a pain, but the things he needed to consider and solve didn't have a clear and perfect answer. So, it always felt like he was only doing things to make the problems go away for a while.