Interesting. What I suggest is to make it an interesting story. Have lots of skills to get the players used to that. As far as combat, since you have two new players, I don't recommend anything that will "throw them for a loop" as most of the combat will. And learning an entire system. I would just use a unique class for the big bad. Like a Black Mage or the Dragoon Archetype that gets the dragon pet. Maybe level him up a bit so it's bigger. Have his minions be a different class and all that good stuff. Make traps and all that stuff throughout, to get them used to playing. A combat encounter with 4 fighters and a black mage would throw them for a loop, since they must worry about the incoming nukes.
I would also like to add that depending on the class should depend a little on what you do for the dungeon. A party without a healer will rely on potions, and quickly encounter the need to have someone dedicated to white magic. If there isn't a thief I would have maybe three traps to give them the feeling of "Oh, we need someone who can take care of that." But if you have a thief then you could have locked doors and all that good stuff to really make them shine.
You also want to try and make them feel like a team. So maybe add somewhere a whole team skill challenge. Where each member must make "X" check to open the next room and whatnot. While that member is holding the level for the door to remain open, someone must go in a pull a level in there. And that spawns some creatures inside and out. So they must fight somewhat separated but still as a group (if that makes sense.) So the whole team is in it, not just one member.
What you do not want, is for the game to have a lot of stuff happening in combat. For encounters to be so "random" in what is going on, that the new players do not know what they are doing, and only the veterans are experiencing what the game is meant for, fun.
I am definitely on board with a difficult dungeon, I enjoy making my games challenging. But try to cater to the entire group, not just the veterans, or the new people. It can be challenging at times. But at least starting at level 5 they won't be too squishy.
I would also like to add that depending on the class should depend a little on what you do for the dungeon. A party without a healer will rely on potions, and quickly encounter the need to have someone dedicated to white magic. If there isn't a thief I would have maybe three traps to give them the feeling of "Oh, we need someone who can take care of that." But if you have a thief then you could have locked doors and all that good stuff to really make them shine.
You also want to try and make them feel like a team. So maybe add somewhere a whole team skill challenge. Where each member must make "X" check to open the next room and whatnot. While that member is holding the level for the door to remain open, someone must go in a pull a level in there. And that spawns some creatures inside and out. So they must fight somewhat separated but still as a group (if that makes sense.) So the whole team is in it, not just one member.
What you do not want, is for the game to have a lot of stuff happening in combat. For encounters to be so "random" in what is going on, that the new players do not know what they are doing, and only the veterans are experiencing what the game is meant for, fun.
I am definitely on board with a difficult dungeon, I enjoy making my games challenging. But try to cater to the entire group, not just the veterans, or the new people. It can be challenging at times. But at least starting at level 5 they won't be too squishy.