Cards with evoke like Shriekmaw and Mulldrifter are excellent ways to get a lot of value out of a creature that is guaranteed to hit the graveyard and trigger Sefris. Likewise, creatures with cycling like Eternal Dragon can be discarded on an opponent's turn to get the cycling effect and push further into the dungeon. To pair with the plentiful cards in our graveyard, the starting list also has a lot of reanimation-focused cards to get these creatures back. Doomed Necromancer and Victimize can help put the most important creatures back onto the battlefield and also sacrifice a creature (triggering Sefris) in the process.

Thorough Investigation can trigger investigate whenever you attack and also let you venture whenever you sacrifice a Clue token. Clue tokens are already powerful as you can sacrifice them to draw cards, which is an effect that is woefully underrepresented in the white color identity. Midnight Pathlighter is a new creature card that will become a kill-on-sight card for your opponents since it makes your creatures unblockable against anything but legendary creatures.

The alternative, monstrous commander for the Dungeons of Death deck is Nihiloor, a mind flayer from the Fifth Edition D&D adventure Waterdeep: Dragon Heist. As a mind flayer, Nihiloor is as terrifying as they are grotesque, and their card captures that perfectly. When Nihiloor enters play, they can tap a creature you control for each opponent and take control of a creature an opponent controls with lesser or equal power than the creature you tapped. This means that, with a strong board, Nihiloor can take control of three creatures when they come into play and swing the game heavily in their favor. Nihiloor even drains an opponent when you attack with one of their creatures, so a deck focused around control magic or threaten effects can be truly terrifying!

Six of the creatures being added to the deck have ways of venturing on their own to help you push through dungeons and complete them at different points in the game. Nadaar and Barrowin both give additional value once a dungeon is completed, so rushing through the Lost Mine of Phandelver in the early game can set you up for a better game later on. Yuan-Ti Malison and Yuan-Ti Fang-Blade both venture when they deal combat damage and come with evasion (in the form of being unblockable and having deathtouch, respectively) so that you can always get in with these creatures.

The other additions to the deck help Sefris of the Hidden Ways trigger her effect as well as fuel your graveyard with the creatures you will resurrect later. Oriq Loremage offers an instant-speed Entomb effect so that you can send a high mana value creature to the grave right before Sefris tries to reanimate a target. Alternatively, Syr Konrad helps you mill cards off the top of your and your opponents' decks and can deal a large amount of damage over the course of the game. Activating Syr Konrad's ability during your opponents' turns can also help Sefris trigger during each players' turn in a round, which is just enough venture triggers to complete a dungeon in a single round.

Living Death and Supreme Verdict both act as board wipes you can use to equalize the board for all players, while Agadeem's Awakening and Living Death can also resurrect your graveyard and end the game. Though not as powerful as other countermagic, Arcane Denial gives you card draw and lessens the blow of the opponent's card being countered by giving them additional cards. In the early game, this means that Arcane Denial can stop an opponent from playing a key card without creating an enemy for the entire game.