So confirming, the hell hounds rolled a stealth check and got that result? I mean I'm pretty sure every party member would be on high alert for danger as we are trying to open the door, so unless they succeeded on stealth I doubt we would be surprised (though I could respect if they got advantage on stealth from the loud banging)
The Hounds were aware of you guys on account of you guys banging on the door to their room knocking it down (throughout which you were not aware of them). In other words, at the start of the encounter they were aware of you (check), and you were not aware of them (check), possibly granting them surprise.
And at the commencement of the encounter, they started barking. I set the passive DC to hear it over the sound of the Fighter tearing open the door at 15, which 3 PCs managed (Rogue, Cleric and Bard).
That's why those PCs are not surprised. Just
before the Hounds appeared on the staircase, the Rogue, Cleric and Bard hear them, meaning they started the encounter aware of the Hounds (so are not surprised).
If Stealth is required (even though the Hounds were down the bottom of a 30' long staircase, 20' away from it, and on the other side of a heavy locked wooden door, in total darkness), they have advantage due to the loud noise, and (being in darkness on the other side of the door) visual perception checks to notice them automatically fail so arguably the DC (if there was one) is even higher at 16 (I set it at 15 to avoid surprise).
Initiative:
Rogue 20
Raven(s): 15
Hellhounds 13
Cleric 12
Bard 9
You (s): 8
Fighter(s): 2
Round 1
The
Rogue goes first. He's standing next to the Bard and close to the Fighter near the entrance (you and the Cleric are standing 20 back from them).
He takes the Aim action, and shoots his bow, hitting a Hellhound dealing 20 points of damage.
Raven goes next. It's now no longer surprised and can take reactions.
Hellhounds go next. Hound one (the wounded one) bounds up to the Fighter/ Bard/ Rogue and breathes fire. The Rogue passes his Dex save (unsurprisingly) and takes no damage (thanks to Evasion). The Bard also passes his save, and the Fighter fails his. 15 Fire damage (reduced to 3 for the Bard on account of passing the save and his magical armor) and 15 for the Fighter.
After finishing its turn, the Scout Rogue moves 15' back with his Skirmisher ability.
Hound two does the same thing, this time only catching the Bard and the Fighter in its breath weapon. The Fighter passes his save, and the Bard fails his this time. 24 points of fire damage, reduced to 12 each.
Hound three moves up to you (the Raven) and the Cleric and does the same. The Bard makes an attack of opportunity against it on the way (the Fighter cant as he is surprised), hitting and dealing 10 points of damage.
The Cleric fails his save. The Raven is likely dead (but feel free to make a save for it).
Please make me a Dex save.
