Building a better medusa

[Sir Brennen]

My own solution is to allow the Medusa to retain her insta-stone variant of Petrifying Gaze (I note it is identical to the Basilisk's gaze; except what I gather is your beef; the part about failing by 5 or more) BUT to say that the petrification isn't complete until the next round AND will be aborted upon the Medusa's death or removal.

Essentially; your idea to give the rest of the party one round to defeat the Medusa is there, only the afflicted target can't participate (he did fail by 5 or more).

If the Medusa is killed or rolled off in a cart or whatever, the petrification wears off by itself over a short rest (1 hour).

Note that the Incapacitated condition can be brought on by a number of other conditions. If the RAW medusa is merely Stunned, that would negate the Petrifying Gaze ability, at least until she recovers. Also, the OP's concept of LOS needing to be retained could be countered by the PCs a number of creative ways.

The idea that the medusa will only last a round of combat is totally dependent on a number of factors, not the least of which is the number and level of the party attacking her. Whether the gaze is a minor or major factor depends on how much distance the group can place between themselves and the medusa, which might be much harder in her twisty, turny lair. If the OP's idea is that this medusa is also a spell caster, she probably would have a few spells to hinder opponents' movement and enhance her own to close distance for her gaze attack. Probably some spells to foil ranged attackers, too. Darkness would be at the top of my list.

She's probably going to last a bit longer if everyone is attacking at disadvantage due to averted eyes. I'd even add a bit of randomness to any spells with area effects, since you can't target well while closing your eyes. You can't hit a creature with Magic Missle if you can't see it. Other spells may have similar restrictions.

 

[Hand of Evil]

Think I would just extend the Petrifying Gaze over a dX rounds, with any additional failures reducing the time by one.

Example, character fails vs. Gaze, rolls a d10, gets a 5 and knows he has 5 rounds to fight. During the next round 1 of 5, the character fails again, so rounds drops by 1, round 2 of 4 now. If he fails the next Gaze attack, he is stone.

This does two things, 1) add suspense and 2) chance for cure (Death of Medusa before curse is complete / Break Enchantment / Stone to Flesh / Remove Curse -- all of these are DM judgment calls I think).