It's entertaining, for sure, and very well done. However, I had an issue with the climactic battle sequence. The DK is given four separate stat blocks as the fight proceeds; in the first, he's got 32 HP; the second and third, 28 HP; and the fourth, "28 (minus dmg already caused)". The only "escape" out of the fight comes after we get to the fourth stat block. The wording, along with the changing HP in the stat blocks, seems to imply damage done has no effect on him, or removes only 4 HP, until late in the fight.
Since the first part of the fight is broken out by round, I expected every outcome of each of those rounds to be enumerated. So, if "He's down" isn't listed as an option, then the obvious conclusion is he can't be down yet.
I don't know if this is an error in the wording, or an oversight in the options, or if the DK magically regains hit points up to 28 after each of the first three rounds, but I found it confusing -- I pulverized the guy and yet the only option was to keep on fighting. And so I wasted a bunch of time trying to figure out what was supposed to happen here, which was frustrating.
I came in as a L2 high-dex light cleric, succeeded on the stealth check getting into the room (first time in the game, I think -- clanky armor gave me away every other time), got a surprise round, won initiative, and for those two rounds I hit with two guiding bolts in a row for 33 points in damage, and ... there was no indication in the choice lists that I could do anything except go on enduring attack after attack by the DK, who was at negative hit points by that time. Second round in initiative order, a high roll on Radiance of the Dawn put him down to -21 hit points (all radiant damage) -- but he went right on attacking; there was no option for ending the fight, until I finally got to DukeItOut.
He's a heavily modified monster, so referring to the MM to figure out whether he was using some kind of magical healing which should have been mentioned, or if there were just some choices missing from the action lists, didn't help.