You Died

In the two months that the Mutant Monster Gecko was bound, Krune was creating a cage that would trap it after it finished evolving. It was a simple setup, but thanks to his ingenuity, Krune managed to install a locking mechanism that would constrict the Mutant Monster Gecko after it finished evolving.

Then again, if he had placed it while it was evolving, its bulging body might burst. So, the cage had to be kept during the final moments of its evolution. Plus, it had to be fast and perfectly functional. Otherwise, he would lose his life. 

Not only that, but it should have enough weight to fully immobilize the Mutant Monster Gecko that would have evolved to a King. And well, that was precisely what he had used now. Even though the Mutant Monster Gecko had surpassed his expectations and became a Monster Gecko Emperor, his cage was still barely enough to hold it in place.