Surviving thousand deaths
In the beginning, Jason didn't feel any kind of pain at all, and he thought that his teacher had been exaggerating the effect of the devilish valkyrie-shield fruit when a small silver shining membrane enveloped him from inside out.
After he had been completely enveloped and everything was sealed-off safely, his body began to itch lightly, which was only a little uncomfortable to Jason
This itching became more apparent as only a few seconds later it suddenly felt more like a sharp knife was stabbed in every cell of his body.
He couldn't focus on refining his brain or splitting it due to the searing pain that became even worse over time.
Not only it felt as if he was being stabbed continuously but also as if he was being skinned alive, burned, drowned, his nails torn out, eyes ripped apart, his brain thrown into a mixer, and additionally a hundred different types of killing methods that tortured him.