Grandpa tries to explain what just happened and what they are up against. After which he will make sure to be in the back of the line for entering. Black will stay near Storm again.

Black pushes through into the library to stand near Storm as Grandpa retreats as far as he can to the stairs down.

The door above opens, and Bryn has time to say "Oh, fu-" before a flash of flame erupts on the floor you're all on, washing over you.

((DEX Saves for everyone except BB and Black, DC 14 or take 34 fire damage. Larry and Storm will be making them at advantage as they aren't in the main hallway where it goes off.))

BB hears/feels the explosion above him, and can see the flash of flame in the stairwell up to the second floor.

Bryn DEX: 9
Bolt DEX: 5 (resistance)
Storm DEX: 19 (can absorb elements for resistance) WIS (15): 5
Larry DEX: 20

Bolt 20 
BB 18
Bryn 15 (ray of frost held for anything else attacking Grandpa, or within sight up the stairs)
Larry 14 
Grandpa 13
Grandpa's Stairway Friend 9
Keller 7 <---<< 
Storm 4 <---<< 

The flames wash over Bryn and Bolt, both are still up, and Bryn looses his held attack. "I can't see anything!"

Attack: 15 Damage: 11

Larry avoids the worst of it, and the flames stop just short of Black.

Storm dodges while shrouding himself in protective magics. (Damage reduced to 8 fire.) Tides Surge: 26

Bolt 20 
BB 18
Bryn 15
Larry 14 
Grandpa 13 (DEX Save)
Grandpa's Stairway Friend 9
Keller 7 <---<< (DEX Save)
Storm 4 <---<< 

Seven darts of force spring out of Storm, further blasting apart the dead duergar and bugs as he seethes with anger. He seems to be fully in the grip of his cursed weapon as he stalks into the hallway, enraged eyes sweeping across his burnt and charred command, dismissing you as the cause of the fire, before turning his gaze to the stairwell and picking up speed and he heads up it.

Bolt 20 
BB 18
Bryn 15
Larry 14 
Grandpa 13 (DEX Save)
Grandpa's Stairway Friend 9
Keller 7 <---<< (DEX Save)
Storm 4 

Keller dex save: 9

The rogue is somehow caught flat-footed and takes the full brunt of the damage. He is in very, very bad shape. He fumbles in his smoking bag, makes sure he is not still on fire, and pulls out a healing potion. He drinks it for 6hp

((Even with a Save and Resistance, Grandpa's going down, though he didn't use his action last turn, I'd allow a retro action if you wished, Secretfool.))

"Ahhhhh, someone blew crap up and I missed it."

((Keller, you wanting to use any movement, or just drinking potion?))

Dex save: 7

Should not have wasted that d20:P ah well. Gramps is down even with the saved roll indeed. No need to retro anything. ((I wasn't necessarily planning on walking to the back though, more wait till the rest passes. but even where gramps was before he would go down so doesn't change much.))

Grandpa slumps to the ground, singed mightily, Black moving to his side, a pleading whine in their throat as they lick at Grandpa.

Black Medicine Check: 9

Bolt pats herself down, "Grandpa's down! I don't have anything to bring him up!"

She'll drag Grandpa into the library, seeking to get him past any potential follow up fireballs.

Bolt 20
BB 18 <---<< 
Bryn 15 <---<< 
Larry 14  <---<< 
Grandpa 13  <---<< 
Grandpa's Stairway Friend 9
Keller 7 
Storm 4 

"You, metal man, can you heal him?", the elf-halfling-dragonborn asks Larry as she tries to tend to Grandpa.

Medicine Check: 2

"I don't have anything either, I'm backing up the Commander. If we can get him out of his rage, he may be able to help.", Bryn says before moving up the stairs.

Bolt 20
BB 18 <---<< 
Bryn 15
Larry 14  <---<< 
Grandpa 13  <---<< 
Grandpa's Stairway Friend 9
Keller 7 
Storm 4 

Grandpa gives a pained shudder as Bolt struggles with fingers she's unaccustomed to as she accidentally jabs him in the neck.

(no mechanical result to Grandpa, but Bolt is hesitant to try again.)

Keller would also go into the library, as he is one neck jab away from dropping as well. He looks to the others and says to whoever looks healthiest, “you’re up. Either decide to close the door to keep that horror away and buy time to patch ourselves together, or find some quicker healing potions and get this last push done to take out the mage and the beast. The commander is in a rage, and I am near dead from that blast.”

Larry looks up, and around the room. ((Would he know if and where the Mistress keeps healing potions, if any?)). If he can grab one, he will administer it on Grandpa. If he can’t, then he will attempt to stabilise the man…

Medicine check: 16 

BB continues out and up.

Keller moved into the library before Bolt moved Grandpa in.

Larry would know that the Mistress would have kept any healing potions where she was most likely to need them... in her workshop in the floor above. Papercuts in the library rarely were severe enough to require immediate healing. There's a chance that the infiltrators haven't discovered the cache she had up there, though she made sure to show you in case a mishap brought her to death's brink and if fell on you to bring her back.

In the meantime, you manage to stabilize the old grey gnome.

BB runs up the outside of the stairwell, and is able to peer in the window, and only sees a hallway awash in charred bits of corspes and smoking viscera. The glass of the windows have been blown out, and smoke and the stench of burnt meat and hair is still wafting out. He sees none of his company. If they are all now painting the walls, it falls on him to complete the mission....

Though he would have expected more blue scraps of skin if Bolt, Storm and Bryn all got blown up.

((Does it mean anything that the three blue characters have all left the game??))

There is a cry of surprise that echoes down the stairwell, and BB and the others can recognize it as Storm's.

Attack: 11 Damage: 16

Bolt 20
BB 18  
Bryn 15
Larry 14  
Grandpa 13 
Grandpa's Stairway Friend 9
Keller 7 
Storm 4 

There is a fwoosh of magic and pained cries from Storm before a door slams shut, and Storm's frustrated bellow can be heard.

3 darts at :4 force

There's the reverberating sound of him hacking at the door.

Attack: 24 Damage: 20

((Oh, shit! I had him use Thuderous Smite on the door and he crit!))

There's a thunderous explosion echoing down the stairwell as Storm. Unseen by anyone but Bryn, he smote the door, blowing it off its hinges into the room.

DEX Save: 11
DEX Save: 15

Door Bludgeoning: 6, CONC: 4