Unlike most companions, the three malgems will attack to defend you, so they will help you with anything you need to do along the way, but you do have a time limit.
Touching the Wavetouched Idol will summon two waves of three Fuming Elementals, then Vapus. With the help of the three Malgems you have a chance, but any adds will end that. Be sure to clear any jaguars around the idol before you activate it.