I ran through my first playtest session last night, it was brief, we covered several of the changes, some of the new features and discussed older editions (A lot of discussion about how 5e feels like 3e). After a long time spent talking and preparing, we started to roleplay our playtest characters, got into motivations and choosing a hook that everyone agreed upon.
Then we got to encounter A and rolled initiative. The players knocked down 5 kobolds in the first round before they could act. A breakdown of rolls went something like this:
The Fighter missed but killed a Kobold due to "close call" from his Reaper feat.
The Wizard used magic missile and subdued one rolling minimum 2 from 1d4+1 reduced the Kobold to 0 and there is no staggered in 5e so he died.
The Rogue used stealth and attacked with Advantage and rolled high, applying sneak attack damage.
The Knight Cleric also rolled high on his d20, although he has the lowest to-hit at +4.
The Healer Cleric, "lanced" a kobold dead, also with a higher than average roll.
When the Kobolds turn came around, they were outnumbered 3 to 5, so I rolled 6 on 1d4+4 for reinforcements, just so that I could use their "Strength in numbers" ability.
From page 6 in the CoC document, Kobolds have two attacks, Spear +0 and dagger +2. I also used the Bestiary document and found two attacks with different modifiers, Spear +0 and dagger +1. From the HTP document, I found rules for daggers as Finesse and Ranged weapons, substituting Dex for to-hit and damage. Since I have no way of knowing if the Kobolds are trained in daggers, like the Rogue, it seems that the +2 to hit and 1d4+2 damage seems like the best option for Kobolds to do the most damage but if the Kobold is trained it could be +4 or even +5 to hit at this low level.
So each kobold attacked with +2 to hit and Advantage. I sent 4 against the Fighter and 4 against the Melee Cleric because they were front-liners and never rolled higher than 12 on 16d20. For this reason alone, the strength of the Kobolds was lost on the player immediately.
In round 2, only one miss from the party, 4 down and 5 left.
So the Kobolds lost their Advantage when their attack turns came along.
All 5 remaining Kobolds attacked the fighter and only 2 hit with low damage, 2d4+4 only gave 7 damage.
In round 3, all the Kobolds were finished and the party took a short rest only healing the Fighter 6hp due to rolling low on 1d12+2 but they decided to head out without spending additional resources to heal a single hitpoint.
In area 1 they avoided the trap but also failed to activate the Kobolds in the other room and managed to sneak into the Garbage room and became swarmed by the rats immediately. The Fighter dropped the Dire Rat with one hit from 5hp to -12hp and didn’t even roll max. The Rats did a lot of damage to the Fighter who was the closest to the trash and had quite a lead on the other players so it was difficult to justify them attacking anyone else. Plus, when they all 18 attacked the Fighter, all attacks were with Advantage, which even though many of their bites hit, the damage was low and the Fighter sucked it up.
The Wizard asked very politely if he could, “light up the Fighter”, and the Fighter, although it could have dropped him at that moment, elected to be hit with Burning hands. With half damage on a miss, and the fighter failed his check, all the rats were eliminated with one spell. Nice and neat. Cure Light Wounds from the cleric, helped the Fighter get back up a little but still not to full. Also, the note about the garbage lighting on fire, I elected to play out the worst case scenario, all the players ran from the blaze, black smoke poured out of the room. They ran into the trapped room to find the Kobolds had been alerted by the smoke and I had plans to bring on the Guards and Chieftain from two other encounters since the smoke was getting really bad. We rolled initiative but it was late and we had to stop.