"Burns the stake" is a phrase with a violent connotation that refers to a process of committing someone to a fiery execution. There are a number of synonyms that can be used to describe this process in slightly less graphic terms. Among them are "immolates" or "set ablaze", which both suggest the act of lighting a fire as opposed to the act of burning someone alive. Other synonyms include "combusts" or "incinerates", which describe the process of reducing something to ashes. Ultimately, the choice of synonyms will depend on the tone and context of the writing.