I get that he's on time limit due to the poisoning but burning him alive didn't feel satisfactory. I was thinking dismemberment like what happened to Kakeru or something a bit more creative. Anyways I'm surprise that this is ending... I hope so. Thanks for the translations.
dismemberment only cause pain on initial damage but will get numb down due to shock and adrenaline. plus you will die faster because of blood loss.
burning him alive but only on near third degree burn is the most painful torture. you bleeding is cauterized so you are unlikely die due blood loss but still feel pain and burning sensation as the neuron still firing to your brain not all your nerves and pain sensory got destroyed. so you can make them suffer but barely alive longer.
if you had experience a cut from knife and hand got burn touching hot object/ hot water, you know with one that have longer pain and unbearable sensation.
death by fire is one of the worse death. even the main punishment in hell is hellfire in most main religions.