Would love more details on how things shook out this way. Why didn't they just shoot him/stab him to death? Did Glassstaff win initiative and then cast Sleep or something? Did he Levitate out of their reach and they only had melee weapons? Etc.
The party consisted of a Paladin, Druid, Ranger, and Rogue (with another Ranger who got called in to work mid-session, so he was taking a short rest while all this went down). Instead of having the Redbrand Ruffians a group of troublemakers in the town like in the book, I decided that I'd make Phandalin a full-on police state: a palisade around the town, watchtowers set up, and a bunch of weaker bandits (CR 1/8) to patrol and keep the townsfolk in line. The chain of command went Glasstaff > Blackaxe (the aforementioned CR 4 barbarian who was the face of the operation) > Lucius and Leyara (two CR 2 berserker twins who were lieutenants, responsible for keeping the townspeople in check).
The party had been captured in their first day in town after picking a fight with Lucius, recovered their weapons that were confiscated at the gate (although they managed to conceal a couple of daggers, a couple of swords, and a handaxe), and infiltrated Tresendar Manor. Along the way they killed Leyara and Blackaxe, as well as finding the hidden satchel with gold and a potion of invisibility, so spirits were high.
I think about now would be a good time to mention the mechanical changes I made to Glasstaff. Because of his Staff of Defense, his base AC was 13, and he could further increase it to 16 by casting
Mage Armor from his staff (consuming one of 10 charges). He could also consume 2 charges from his staff to cast
Shield. Normally, his spells are as follows:
Cantrips: Light, mage hand, shocking grasp
1st-level Spells (4 slots): Charm person, magic missile
2nd-level Spells (3 slots): Hold person, misty step
However, I figured that he'd be focused more on defense and control than offense, so I modified his spell list:
Cantrips: Friends, light, mage hand, minor illusion
1st-level Spells (4 slots): Charm person, grease, magic missile
2nd-level Spells (3 slots): Crown of madness, hold person, misty step, shatter
I also gave him the Alert feat, and locked his doors with Arcane Locks (Bandits are unreliable at best, so having the locks was an easy solution to why Blackaxe didn't kill him in his sleep and take over the operation). His
scroll of fireball I changed to a
scroll of hypnotic pattern, since I play my NPCs as being out to defeat the PCs at any cost (within their own limitations, of course), and a fireball would murder the whole party if he read the scroll, whereas everyone has decent Wis saves to resist hypnotic pattern. His familiar became a raven instead of a rat, and there were holes near the ceiling above the secret door so that his familiar could fly out and bring messages to the rest of the bandits.
Having been beaten up by the bandits, both before their arrest and in the manor, the party was pretty low on HP at this point. They'd been told where Glasstaff's quarters were, but not how to get in. After they tried to pick the lock on the secret door (and failed), they tried to break in the main door (and also failed). Talking through the door, Glasstaff expressed his disappointment that they'd been destabilizing his power structure, and after some conversation the PCs withdrew to discuss their options. Glasstaff wanted the paladin's head (not attached) since he took Blackaxe's, so they decided that the ranger would drink the Potion of Invisibility that they found beforehand, and when the door opened to let the paladin in, he'd sneak in as well, kill Glasstaff, and all would be done. The druid turned into a spider and crawled into Glasstaff's quarters through the holes for the familiar, while the rogue would try to get in the back way (because he didn't know the door was magically locked the first time, I gave him one more attempt to try and open it). The paladin was adamant that he'd be the one to take the fall for Blackaxe, since he'd rather die than see his allies dead. Glasstaff heard that last bit...
The paladin and ranger's plan started off terribly. Glasstaff didn't open the door and invite the paladin in, instead he cracked the door open and lobbed a
magic missile spell at him (wounding him but not dealing too much damage). Thinking quickly, the ranger grabbed the door and threw it open before it could be slammed shut, and so Glasstaff retreated to the corner of his lab, out of reach of the paladin. The initiative order was extremely odd: the Paladin went first, and Glasstaff (despite Alert) went last.
The party converged on him but didn't get high enough attack rolls to bypass his first two shields, so on his turns he first used Shatter (catching the druid, paladin and ranger, but dealing really low damage) then Crown of Madness, charming the paladin as the rogue joined the fight. Why the paladin? Not only because the paladin was the heaviest hitter, but also because the paladin would rather die than see his allies dead--and Glasstaff is a sadistic bastard. The paladin hit the ranger on his first turn and missed on the second (in these two turns, Glasstaff took a couple of hits but passed all his Concentration checks). Having only one shield left in his staff (but having 3 1st-level slots and 1 2nd-level slot), Glasstaff dismissed the Crown of Madness and used his
scroll of hypnotic pattern... Which everyone but the druid failed their save for.
At this point I'm going to take a step back and describe the current situation: This fight was taking place in the laboratory, so the first
Shatter destroyed the table and alchemical equipment. Shards of wood and glass and foul fluids all over the floor. Glasstaff's staff is nearly drained of charges, but he has most of his spell slots left. His health has been whittled away by the last few hits so he's within one solid hit of death. The paladin, ranger, and rogue are all barely conscious, as well as being hypnotized by the hypnotic pattern (incapacitated and speed drops to 0... They've entered a vegetative state). The druid is also barely conscious, but it's his initiative count. He could run, he could fight, or he could try to wake up his allies. Having seen that Poison Spray was his best bet for bypassing Glasstaff's shield, he decided to use Thorn Whip... Which surpassed Glasstaff's base AC, but his last shield was consumed deflecting the attack.
Glasstaff dropped the druid with
magic missile, before going on to the rogue and ranger. The druid failed his first save and got a nat 1 on the second, the rogue died on his 4th save, the ranger passed all 3 of his saves. Seeing that the druid and rogue were dead and the ranger was stable, Glasstaff (having a single 2nd-level spell slot and 5HP at this point) dismissed his concentration, let the Paladin see his allies were dead or dying (because psychological torture!) and used his last spell slot for another
Shatter. The corpses and their equipment were pulverized, the Paladin failed his save and was dropped to 0 hit points, and the Ranger had to make MORE death saves... But luckily they both stabilized.
Afterwards, the player of the Paladin decided that he's going to change his god from Mielikki (goddess of forests) to Tyr (god of justice), and when he wakes up he'll swear the Oath of Vengeance over the bodies of his fallen comrades.
To answer your original question, they
tried to shoot/stab him to death, but the Staff of Defense bumped his AC to ridiculously high levels. Hitting AC 21 is extremely difficult, and he didn't have to conserve the staff's charges for later encounters. His initiative was at the very bottom of the order, which was a HUGE boost because his shields (including his first) were up for everyone else's turns as opposed to breaking halfway through the round. It never hurt that everyone rolled poorly on their saves, either.
