A terrible idea flashed in Lukas' mind. But, quite frankly, there weren't any better options. He was greatly limited by the ghast's maw crushing most of his body. Of course, any other idea would have been more self-preserving than this... but he could always undo his mistakes, right? So long as he didn't die, at least.
He mentally prepared himself and physically prepared himself as much as he could. The plan wasn't complicated, only slightly reckless. His plan was to force himself completely inside the ghast's maw, hopefully without crushing any part of himself in its bite strength. Once inside, he was to worm his way down to the heart in its throat and mercilessly hack and slash at it until it stopped moving.
His main hope was not to be crushed or swallowed in the process. He wasn't even sure if ghasts had organs, stomachs, or anything like that, but now was not the time to test that theory.