This will make sense if you were there, or if you know the scenario... And obviously there are spoilers within!
[Spoilers for 'The Lost Mine of Phandalin']The scenario begins with the group being ambushed by four Goblins. I was rolling pretty badly, and the players adopted a tactic of working together: one would hack apart the bush the Goblins would hide behind, the other one would then attack the exposed Goblins.
(klik played the wizard, and they have now cantrips (spells that you can do as often as you want) that do (some) damage. Her favourite was Ray of Frost. The rules state that it has a verbal component: the wizard must speak to unleash the spell. Of course, the words to accompany this spell were "Adiabatic expansion!")
The group captured one of the gobs, and disposed of it when they interrogated it -- Theodoor, the Noble Fighter had some moral qualms about it at first, but once Roscoe the Rogue had done the dirty deed, there was to be no mercy for the goblins expected in the rest of the session -- in fact, they did some pretty gruesome stuff, completely unprovoked by me, the innocent DM!
They found the trail, and the Rogue discovered the traps -- by triggering them and then making his Dex save to jump out of the way just in time... They also discovered the sentries near the mouth of the cave and surprised them, making short work of them. They saw the wolves, and using fresh Goblin meat, Koriel the Folk Hero Fighter managed to pacify the wolves.
Thruldurian the Cleric cast Light, and the second in the marching order carried that with him. So when they rounded the corner, the Goblin who was on the look-out on the bridge was not sure if he saw something or not (because Koriel obscured most of the light). Hadriel, the Elf Wizard, did see the Goblin, but missed with the, by now infamous, Adiabatic Expansion. So now the Goblin knew for sure someone was there, so he shouted to the Goblins stationed at the waterfall to release the flood. Hadriel speaks Goblin, so he could warn the others, and they ducked into the wolves' den to let the flood pass by.
Roscoe managed to climb up the chimney into the lair of the hobgoblin leader undetected, and fastened a rope to a stalagmite to allow Koriel and Hadriel (the other two characters with some stealth capabilities) to climb up as well. (I ruled that using the rope, they would not have to roll for climbing up the slope, but they did have to roll for Stealth, which they both rolled over Klarg's passive Perception score.)
Hadriel then cast Predistigation to create the sound of falling rocks over Klarg's bed, so everyone present turned their attention to the other end of the room. Then the three initiated the attack, while Theodoor and Truldurian would climb up during the surprise round and join the fray. Excellent shots by Koriel and Roscoe, along with an Adiabatic Expansion from Hadriel meant that Klarg went down within one round! The wolf and the one brave Goblin gave the party some trouble, but they managed to kill them without taking damage! I was rolling rather badly at this point...
Just when he dropped one Goblin, Theodoor roared to the second, scared one, to intimidate him. But he was the only one left alive, and I ruled he got mad with fear. Gripping his scimitar in both hands, the Goblin charged towards Theodoor and attacked! And wouldn't you know it: I rolled a critical on that attack, wounding Theodoor quite a bit! But an arrow from Koriel and a hammer strike from Thruldurian brought him down too.
After a quick survey of the room, they checked the waterfall room. The Goblins there were at full alert: they had released a flood, and after that the intruders had not been seen again. Perhaps they had been flushed out, perhaps they would come back? So they were quite focussed towards the stream, and had their backs turned to Klarg's den. The noise of the waterfall meant they hadn't heard any fighting, so they were easy prey.
But the party had gotten confident that they could take these Goblins, and wanted to demoralise them some more. So they chopped off Klarg's head and put it on a stake! Thruldurian then cast Light on it, so that the severed head could be seen clearly in the dark caves, and Hadriel cast Predistigation on the head to have it make eerie music to add to the effect.
I'm not sure what prompted this blood-thirsty and savage plan: it sort of happened with not one person making the decision, but everyone chipping in (so to speak). Within two hours, players who had never played together before came together as a team of professional murder hobos -- I didn't know if I should be proud or disturbed by their thirst for blood...
The group then made short work of the three Goblins near the waterfall, and then the party sort-of split up... Koriel, Roscoe (with Klarg's head) and Hadriel marched to the bridge, scaring the lookout who then retreated to the Goblin den. Theodoor and Thruldurian followed the stream down and tried to climb onto the ledge, but it could not support the weight of the dwarf in full armour and crumbled. They doubled back and took the bridge, bringing up the rear.
Yeemik, the Goblin leader, was in a bit of a bind: the scenario suggests that he hates Klarg and that he will use Sildar to bargain with the party to have Klarg killed. But with Klarg's severed head being paraded in front of him, he lost only could threaten to kill Sildar. The party was not impressed, and made short work of the Goblins, Yeemik included. The two last Goblins surrendered, but they could not expect any mercy. So when the first one went down, the second one decided he had nothing to lose, so he picked up his scimitar and attacked -- and hit Theodoor! He didn't get a second chance to do so, however.
And that meant there was no Goblin left alive in the Cragmaw Hideout! Thruldurian healed some party members, and they had a short rest while they patched up Sildar and let him do his story. With the extra supplies and the treasure they found, the group then made their way to Phandalin, with Sildar in tow...
Everyone had a good time -- and that's a good sign! I decided to go with "say yes or roll the dice" for this session, and that worked out quite nicely.
I'm also quite pleased with the rules. It's so much simpler than D&D3.5 or Pathfinder: no more tactical grid combat! Rules for surprise are simple, no more 'flat-footed' AC to keep track of, no more 'ranged touch attacks' or weirdness like that... There are only a few 'skills': most things are resolved with an ability check. That runs much faster, because there's less 'clutter'.
Two rules merit special mention because they're awesome. The first is Passive Perception: the average of your Perception rolls. That means that if you're not actively searching for something, you only notice something if your Passive Perception is over the DC to notice it. That means I, as a DM, don't have to get everyone to roll on their perception for stuff like noticing traps if they're just following the trail. That speeds up things considerably, and also does not alert the players that something is afoot, which I like as well.
The other is Advantage/Disadvantage. In special circumstances, you can get an Advantage on a roll. In that case, you roll two dice for your ability check or attack roll, and take the highest. If you get a Disadvantage, you also roll two dice but you get to take the lower one. This rule makes it incredibly easy for the DM to give a bonus or a malus on an action, without having to give a precise plus or minus on a roll -- again, speeding things up.
I'm looking forward to the second session. I'm also looking forward to the first session of the second group: I'm really curious to see what they do, and if they do something differently from the other party...