Entered into Vault of Archavon as a Rogue having never played an mmo outside of Runescape and just remember how awesome it felt to walk into the place. It had the same Ulduar theme as Halls of Lightning (one of my favorite dungeons) and just gives me chills to this day as I remember back to that feeling of seeing monsters so huge that required such a group to take down and the perceived chaos of the pug I was in with Archavon who I now see as incredibly simplistic but then it was a mountain to be tackled.
No add-ons or anything, probably doing absolutely terrible dps, and somehow ended up alive through the fight. I felt amazing after killing that boss and was excited when I actually ended up meeting the GM of a guild I joined shortly after to start raiding Naxx a few weeks later.
Talk about rose-tinted glasses, they're on hardcore when I start thinking about my first adventures raiding lol.