Have you played the module (blind)? It's not so much that anything happened at the door, it's that we managed to get it open. It doesn't take you long to get paranoid, shaking, and energized by Tomb of Horrors.
Not sure I've ever had the pleasure. If you can call paranoia, shakes, and engergized "pleasure."
Tarkus was the man villain behind the scenes during the first 2+ years of my current campaign. He had been introduced even in the back story of one of the PC's, and was known to be necromancer involved in some dark and mysterious work. All plot threads seemed to connect to the mysterious Tarkus. Unbeknownst to my players, Tarkus had been introduced to them in session 1 of the campaign as the neighborly undertaker Master Findel who lived beside the parties Cleric. I had managed to work several conversations with Tarkus into the game, and at one point they'd even sought him out as a resource - since he proved 'surprisingly knowledgeable and well educated'. Tarkus in turn covertly made several attempts on the life of the party and did kill one of the Priest's other neighbors, a seemstress, and as his signature ability was known for summoning large numbers of Hell Hounds (which at one point involved a chase over the roof tops of the city as the party fled a pack of hellhounds). Eventually however, their suspicions regarding Master Findel awoke, and investigations lead to a series of increasingly violent confrontations and eventually fireballs and small armies of the city guard. Tarkus managed to escape each encounter, however the party learned Tarkus's motive and means. He was in the city on the behalf of the even more mysterious Keeropus to obtain from the Lower Catacombs, indeed from the tomb of a Menes III, a sample of Dark Fire to be used in powering the still mysterious engine Keeropus was known to be creating. This was the same Lower Catacombs where at a sealed entrance they'd discovered a rune warning that behind this seal lay necromantic hazards that poised a threat to the very existence of life. To this end Tarkus had arranged over the course of the prior two years to tunnel into the Lower Catacombs, and was now searching for the Dark Fire in their labyrinthine depths. The party attempted to head him off by finding the dark fire first, encouraged and aided in this plan by their contact the Wizard Master Aiden who served as a sort of 'fix it' man for His Benevolent Despot Falster Dikelgard. Long story short, after several forays into the catacombs, the tomb of Menes the III was breached and the dark fire extinguished just minutes ahead of Tarkus. Tarkus - unaware that his quest was now futile - proceded to engage the party in an epic fight involving Hell Hounds, Juju Zombies, and fiendish wolves (and fireballs and various necromantic nastiness) that resulted in one PC death and which only avoided a second by the expenditure of a destiny point and timely divine intervention in the form of an angel of Showna (the Sun goddess) before finally taking a sword through the back as his pets were beaten down. In short, I managed to pull off the sort of epic reoccurring villain that I'd been striving to pull off (without cheating mind you) since I was a kid and much high fiving and hooraying occurred.
Can Modos do it:
Necromancer: yes, that's just a spell selection question.
Summoning Hellhounds: I'll include Summon in the original spell selection.
Investigations: Detect, Knowledge-Scholarship, or Profession skills would help.
Dark Fire: sounds like a magic item. Modos magic items are currently granting character features (ability, skill, or perk) to characters, or acting, mechanically, as NPCs.
Mysterious engine: there are no movement rates in Modos core. So the speed of the engine, and what it could do, would be up to the GM. However, when things are difficult to damage (like armor), they have Protection, which is a die that reduces incoming damage.
Juju Zombie and Fiendish Wolves: the new rulebook will have a section on creating monsters.
One PC death: Modos doesn't have dead PCs. The closest a PC can get to death is Mostly Dead.
Destiny point: hero points. Roll 1d6, in most cases, to gain a skill bonus.
Divine Intervention: no rules for that beyond rule 0. I don't want to include incorporeality rules, but it could be fun to draw up a monster or two with that feature.
Sword through the back: no hit location in Modos, but there will be guidance that crippling wounds don't happen until a character is very low on, or out of, hit points.
Thanks James...your input's next on the examination table!