Hey I just have a question about specifically how gaze attacks work, for a medusa specifically, but also in general as there is the one in the 2nd book as well. I know the description says on the universal rule but I just wanted some conformation of this.
It says that its a 30 ft radius and that everyone has to make a save on their turn if they are within range, unless they make special efforts to avoid looking at the creature. But how would you explain that to the party? Mechanically it functions just a 30ft aura basically right, because of all around awareness in table top stuff?
Would you say you feel overwhelmed looking into that creatures eyes and for a medusa you feel you body ache as all at once if feel like every part of you starts to shout out in pain. I mean I know all my players know what a medusa is, but there characters may not be so familiar.
I could explain the mechanics on averting their gaze, but how would their characters know that?
Then as the gaze description says, the monster can actively try to gaze at someone, that is just them using their standard action to do so right or is that a free action once per turn?
Yes, everyone needs to make a save on their turn if they are within range. The default assumption is that each character is looking this way and that throughout the round and they will look at the medusa (etc) unless they take specific countermeasures, like not looking in that direction.
If an ability doesn't have an action type listed, that (generally) means it's a standard action. There are a few cases where this results in some very unclear things--the harpy entry, for example--but in this case, it's pretty clear. The default area-effect gaze is free, and specifically inflicting your gaze on someone and forcing a second save is a standard action.
Regarding warning the players, you've got some flexibility here as the GM. You can adjust your approach as-needed. I've used at least three options:
1. The characters might recognize the medusa themselves, with an identification check. If they do identify that the creature has a gaze attack, you can explain to the players how gaze attacks work in terms of Pathfinder mechanics as part of that conversation.
2. If you're feeling generous, you might warn the characters before they need to make a decision on gaze countermeasures. I probably wouldn't describe it as pain, myself--I usually describe a milder version of the condition they'd get, like feeling slow or heavy--but this is entirely up to you as to how you want to describe it and how you can best communicate with the players. It's part of your GMing style!
3. If you're feeling less generous--for example, if you think the party has previously had a chance to learn about the existence of the medusa; if solutions for petrification are easily available, and you think the party can easily survive the encounter without their full complement; or if you're just running a higher-difficulty game with more experienced players--you can always have them learn about the gaze attack the same way most people in Golarion and in other settings probably do. In other words, they might see their friend turn to stone before their very eyes, without any warning at all! At which point you can then have the gaze attack countermeasures conversation with the players.
These are all viable options with benefits and drawbacks, and determine the kind of experience your players will have at your table. It sounds like you're leaning toward #2, and it can definitely work.