The walk back to Mystic Camp was long and painful, mainly for Lukas.
Due to the fight with the ghast, Lukas had retained a limping walk from hurting one of his ankles. His right arm and side still hurt as well, but it was just a bit of soreness from a rough landing. He was also incredibly drained.
Remembering back on the fight, Lukas was fairly certain he had at least another 15 seconds until it would have been safe to use his Rewind Frequency again. But, of course, he didn't and paid the price for it. Though it had been a while since he tested these limits, and so he had forgotten just how draining they truly were.
Axel too, was tired, though Lukas was sure who was worse off. He had complained about how tired he was, and yet he was the one to finish the fight. Moreover, Axel had done so with movement that didn't at all seem sluggish or slowed by exhaustion. Perhaps his fatigue was more mental, while Lukas' was more physical.