Antonyms for the phrase "vaults up" would imply movements that are diametrically opposite to the idea of jumping or leaping upwards. Synonyms for this phrase could include crouching down, slumping over, or sinking down. Antonyms could include actions such as sinking down, collapsing, or falling to the ground. Alternatively, antonyms could also imply slow, careful, and deliberate movements like creeping, shuffling, or tiptoeing. The word "vaults up" implies an action that is confident, decisive, and forceful. Its antonyms, therefore, would describe movements that are hesitant, uncertain, and indecisive.