Famously, the gaze of a Medusa's eyes turns hapless adventurers to stone.
However, is this save automatic upon seeing her eyes?
The Medusa's Petrifying Gaze feature says (emphasis mine):
Petrifying Gaze. When a creature that can see the medusa's eyes starts its turn within 30 feet of the medusa, the medusa can force it to make a DC 14 Constitution saving throw if the medusa isn't incapacitated and can see the creature.
The text states that the Medusa can force the creature to make a save, implying that the Medusa chooses when this effect takes place. Is this how it works, or is the effect automatic?
For a little more background, currently I am running
Tomb of Annihilation, where Zalkoré has her face hidden behind a translucent veil.
The players can clearly see her eyes, but she hasn't yet decided to activate her ability yet, so no petrification saving throws yet. Am I playing this correctly, RAW?