The preparations took ages.

Scar didn't exactly give Mumbo a clear explanation as to why he had to use iron, but by god was he going to follow that order to the extreme.

So when the wizard saw the prototype, the circuitry looked more like a hunk of iron rather than a functioning circuit. But Mumbo tested it, double checked the wiring and made sure it worked before it memorised it, tore it down, and built it in Grians base while the prankster was working on his manor.

Scar also insisted that Mumbo wear red for reasons beyond him, but Scar was insistent and seemed panicky when he found out Mumbo went to Grians base without the colour...so best to wear it, he decided.

"It's done." He announced in hushed tones as he climbed the ladder into Larrys shell.
And proof of his work was on him- his hair was sticking out in 15 different directions, redstone dust stuck in parts of it. His hands were covered in the dust as well, his fingertips a bit pinker than usual. Iron shards glittered on his clothes, remnants of him breaking and remaking the circuits until they were perfect.

Scar took one look at Mumbo and nodded. "Can you deactivate for now? I still need to prepare."

"Prepare what? You asked me to make a trap man." Mumbo half-laughed, "I mean, I can reroute some of the circuitry to an external power source so it locks the pistons in an unpowered state-" he rambled, quickly becoming lost in his own head.

Scar waved a hand in front of the redstoner a face "Mumbo? Mumbo. Earth to Bumbo Big Baggins."

"Oh- Sorry. Right- I can turn it off for now. Just let me know when you need it on, okay?" He said before heading back to the contraption to deactivate it.

The wizard nodded with a soft sigh, turning away from Mumbo to find that red book again.

Something about that circle of runes felt important and he studied it late into the night. The runes weren't mentioned in any other book he had, nor any reference was made to it. It seemed the only place it appeared was crammed onto the page of an unmarked red book.
In fact, the more he studied the runes, the less certain he was that they were familiar ones. That shape looked similar, but it was ever-so-slightly wrong, the line down too long or slanted the opposite direction. And that one looked familiar too...but it was backwards? The entire matter was confusing, these slightly-off runes used only for this circle and still no explanation as to what it did.

This was hopeless. Scar set the book aside and shrugged on the leather armour again. He had a notebook this time- ready to simply watch Grian. See if he slipped up somehow. Reveal a tad bit too much and give himself away.

Scar was so close to being positive- he just needed one last thing, one last piece of proof. One last reassurance that he was right, that his neighbor wasn't human, that he was fae.
That he wasn't from this world and should be sent back.
There was a reason magic was scarce in the world now. The wizard sighed at the memory before shaking his head as if to clear it.

Besides there was no reason to dwell on the past. After countless hours and sleepless days, Scar had his proof.