combust has 19 distinct synonyms spread across 4 of its 5 senses. Each sense below keeps its own list, because a synonym belongs to a meaning and not to a word: swapping one sense's substitute into another sense's sentence is how a thesaurus makes writing worse. WordNet records no antonym for it — antonymy is a relation between word forms rather than concepts, so it is deliberately sparse.
Counts are distinct word forms across every sense. A synonym that appears under three senses is counted once here and shown three times below, under each sense it belongs to.
cause to burn or combust
“The sun burned off the fog”
get very angry and fly into a rage
“The professor combusted when the student didn't know the answer to a very elementary question”
cause to become violent or angry
“Riots combusted Pakistan after the U.S. air attacks on Afghanistan”
Synonyms, antonyms and the broader and narrower relations for combust come from Princeton University’s WordNet. Full sources and licences.