The rules for a Medusa's Petrifying Gaze reads as follows:
Petrifying Gaze. When a creature that can see the medusa's eyes starts its turn within 30 ft. 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. If the saving throw fails by 5 or more, the creature is instantly petrified. Otherwise, a creature that fails the save begins to turn to stone and is restrained. The restrained creature must repeat the saving throw at the end of its next turn, becoming petrified on a failure or ending the effect on a success. The petrification lasts until the creature is freed by the greater restoration spell or other magic.
Unless surprised, a creature can avert its eyes to avoid the saving throw at the start of its turn. If the creature does so, it can't see the medusa until the start of its next turn, when it can avert its eyes again. If the creature looks at the medusa in the meantime, it must immediately make the save.
If the medusa sees itself reflected on a polished surface within 30 ft. of it and in an area of bright light, the medusa is, due to its curse, affected by its own gaze.
What happens if a creature starts it turn outside of the 30 foot range of the gaze ability, but then moves in closer so as to be within the 30 foot range? Do they have to make a saving throw then or are they unable to be affected by the gaze power since it only applies at the start of their turn?
The rule does mention making the saving throw if they look at the medusa in the meantime, so what if you attack or cast a spell at the medusa which requires looking at it?