The phrase "raise to fever heat" can be replaced with several synonyms, depending on the context. One suitable replacement would be "ignite" or "kindle," which conveys the idea of increasing the intensity of an emotion or action. Other options include "incite," "provoke," "rouse," or "agitate." Each of these synonyms suggests a sense of stimulation or arousal, and they can be used interchangeably to emphasize the act of intensifying a situation or feeling. Overall, selecting the appropriate synonym for "raise to fever heat" requires careful consideration of the intended mood and tone of the communication.