If you're curious how that final encounter played out, the party wandered into a large armory after fighting a bunch of sahuagin (encounters 71 and 72, the latter arriving as reinforcements and getting torn up pretty fast). Encounter 71 took place on either side of a portcullis with the party taking control of it to limit how many could get at them, and some sahuagin spending actions to raise the portcullis by brute force to allow others to shimmy under and when they were killed or pushed back, having to try again. The barbarian/fighter suffered some heavy damage blows (I roll, never use average) including a couple of crits that by fight's end had him at like 8 of 80-something hit points, requiring some healing be spread around just to get him back to about 40-something hps.
Anyway, the party started burning the sahuagin weapons in the armory, and the smoke drew the attention of the force massed in the neighboring barracks. Once a sahuagin came through the adjoining door and saw what was happening it raised the alarm. The party hurried over there, killed that one sahuagin, but quickly saw this new area was clogged with sahuagin and leader types. They decided to try to slowly draw them through the door only taking on a couple at a time. When they were gathered outside the door the ranger/sorcerer cast darkness in the doorway, creating confusion and blockade. As sahuagin stumbled out of the darkness into the scrum they'd get chopped down. But once a Champion and Coral Smasher pushed their way through and used grapple/push to make some room, more sahuagin started to make their way in, since they'd stumble out of the darkness without necessarily immediately having to defend themselves. Meanwhile, streams of sahuagin and other champions and smashers started coming round the long way (which took 2 to 3 rounds depending on the specific route). Oh and somewhere in there a Champion did a disarm maneuver and the barbarian lost his magic great axe as it was flung into the darkness.
When the party realized that more were streaming into the armory behind them, the party decided to withdraw to a small room off the armory with only one way in or out, since now they'd be fighting on two fronts.
Important note: The druid's player could not make the session, so we decided he was wildshaped into a rat and sleeping off a hangover in the gnome's hood (which is in character, and would allow him to "recover" and join the fight as soon as the player returned next session). At this point, the ranger/sorcerer and the gnome bard/wizard were at about 24 of 45 hps.
The session ended with the party bottled into the small room and me deciding the druid woke up to cast Spike Growth outside the little room to slow the waves of sahuagin and cause them damage if they tried to move away.
After that it was a waiting game, as the PCs decided that the sahuagin could afford to wait for more reinforcements and wait out the spell.
Eventually, they were able to push their way out - in part because of the efforts of the gnome who used a potion of spider-climbing to get out into the armory again and rain spells down from above on the trapped sahuagin. A few of them tried to withdraw to a better position and were killed or heavily damaged by the spike growth. At the same time the Saltmarsh militia arrived at the front gate, drawing off reinforcements and the stragglers of those at came around. the barbarian spent three round fumbling in the darkness for his magic axe when the ranger/sorcerer refused to dismiss it.
It was then that the blademaster joined the fight, carrying the barbarian's axe: "You want this back?" It said in broken common. "You'll have to kill me for it!"
And so on. . . By battle's end, the barbarian was unconscious, the party druid was down to 12 (of 60) hps, the ranger/sorcerer was around 7 hps, and the gnome was still hovering in the 20s. The gnome's heat metal made a big difference in the fight against the platemail wearing blademaster.
Fun was had by all, but it was dicey for a while. The fighting between rooms, the withdrawing sahuagin and their coming around different ways, the use of grapple/push to force the PCs back, etc.