Crimson Sands of Time

<ruling based on the written text of the adventure>

Ascending to the upper chamber (with some help from Sam) Tetrevess takes aim at the dome and, a ripple of potent abjuration magic cascades from the point of impact as the disitegration ray is absorbed by the dome.

So is their a door where the blades were? 

"At the far end of the hall, two blade-shaped patches of pitch darkness hover in the air to either side of a double door. A glowing green crystal roughly the size of a human fist is set into the arch above the doorway."

Angus is going to start smashing the projection crystals with the pommel of his magical longsword.

Sam will walk over to the door and try and open it 

Quote from rob88scps2 >>

Angus is going to start smashing the projection crystals with the pommel of his magical longsword.

The crystals are relatively fragile and Angus smashes them easily (this is during combat? I'm just going to call it one turn, mechanics aside> upon smashing the sixth crystal, the glow about the remaining five fades and Everlast ceases to exist.

Quote from Legion4 >>

Sam will walk over to the door and try and open it 

 There's a dome shaped wall of force over the hole, so... how?

<edit: I see reading my descrioti9n above thst i wasn't clear.  The dome absorbs the disitegration magic, remaining sturdy as ever. I'll just point out that there are other ways to get to that door thst don't require removing thst dome of force, though it can be removed.  Swords are still fighting, but this is actually more of a puzzle combat, so, for pbp, I'm less concerned about the mechanics, but you are in danger. Tactical retreat is an option (they won't leave this tower). For now, though, the NPCs have effectively paused the threat so you can overcome the environmental obstacles.

So, first there is a hole in the ceiling, which is blocked by a wall of force.  Once past the hole, there is a door on the other side which is covered by a gem-like substance, and this is our destination, yes?

Would it be possible for someone to retreat out to the invisible bridge and then fly or levitate up and bypass the wall of force to get up to that next level?

Yeah, technically Chad's already on the invisibridge now (per the map, but it's negotiable). Avarice can cast fly, but she's now concentrating on the banishment spell.

Does nobody have misty step or dimension door, etc?  Magic isn't even required for this, really.  

Tetrevess can fly (wings of flying), misty step through the wall of force and then smash the gem- if this is what is protecting the wall of force?

You smash the crystal over the door, which ceases to glow as it cracks and fragments gall from the socket which once held it over the door.  The wall of force vanishes in a blink, the rime which sat upon it falling to the floor around the hike and drifting like a snowfall down the barrow tunnel, falling like snow in the chamber below, where you met Everlast.

LBoD Cha save 14 x Serpent's stare  DC 15

The door is open.

“Well, I feel kind of silly casting disintegrate when I could have just done this, but same effect I guess.  Let’s get to it?”  Tetrevess says. 

Tetrev4ss enters to find a riom rich with the crsckk3 or arcane energy in the air the moment he steps through the door.

Lining the far wall of this hall are eight doors, each marked with a different arcane symbol. On the wall above them is etched an inscription in Draconic.  It reads: "Speak thy master’s name and enter.”

Make a DC17 Con save

Sam will follow “well this is magical to say the least” back to the brain in full plate 

Sam looks a Trev “T you might want to stand back if I get this wrong” then he will wait if he takes his advice then in draconic says “iroilarthas” then brace himself 

Tetrevess Made the Con save with a 26 in log (18+8).

he steps back.  He looks blankly at Sam for a moment, as if confused where he is, then braces himself and grips his staff firmly.  

Nothing happens to Tetrevess.  Nor does anything happen at the mention of the name Iriolarthas. 

Sam, Make a DC17 Con save.

Tetrevess recognizes that the symbols on the doors represent the eight schools of magic. In the library, you might have keatned the names of Iriolarthas’s eight apprentices. Make an arcana check. (Results are variable)

Arcana check 24 in campaign log.    Tetrevess says “ahh.. these symbols represent the eight schools of magic.  Let’s see,  what do I know of this place…”.  

Con save 7