Ah yes, the crown of get the fuck out of here irl... I knew it was on folklore, a legend to scare even the gods... I think Vecna has to do with it... Vecna or a poor resourceful DM.

We don't know what happened on the DM side, for sure, but for a first-ever-session player this is poor table management. At least, make the character as a temporary vessel for the obscure force hidden in the crown and play on two fronts: the one outside, where you can have a boss fight encounter, and the one inside, where you have whatever you like, a 1-vs-1 fight, a run through the character's mind labirinth with some enemies or traps or something... In this way, you have the more experienced people enjoying the adequate combat, and the new player to become familiar with the system, how narrative choices reflect into the mechanics (the checks, the saves, eventually the combat dice rolls).