The deck did not run too smoothly, as expected in a singleton limited format. However, by playing skillfully he 3-4'ed in matches, with a 7-10 game record, which meant the deck worked, at least in some games. We were all, however, appalled by the creativity of that design. It ignited a spark in my head. I wanted to see this more often.
I started looking for ways to enable combo in my cube. There was card drawing and filtering available already, but a total lack of tutors, and not many interactions to be explored. I thought about putting 2-card combos in the cube on purpose, but with that approach it would be risky to draft that combo. Odds were someone else would take the second piece if you took the first, then they would be two dead cards in the pools of two frustrated players. Even if you the two, without redundancy the deck would be extremely vulnerable to disruption. No, I needed a better approach.
Pondering about what allowed the Living Death deck to exist, I identified the following elements:
(1) A card that interacts in very particular ways with a lot of others - Living Death interacts with both players' dead and alive creatures by mass killing and mass reanimating.
(2) Support for that card - Bojuka Bog to prevent the opponent from getting back his dead creatures, Millstone to power up the player's graveyard.
(3) Control - Counterspells and removal so that the player has time to try to find the combo pieces.
(4) Ways to find the combo pieces - card drawing, filtering, scrying.
(5) A plan B - the deck featured some other reanimation cards (Animate Dead, Reanimate) that could be used when Living Death was not found or ended up milled.
(3) and (4) are easy, since these categories already existed in the cube, I just needed to make sure they weren't weakened much. Actually, I could definitely improve (4), so I added Diabolic Tutor, Congregation at Dawn, and plan to add other tutors.
(1) requires cards that combo, or at least have strong synergy with several others. Ajani's Pridemate, Manabarbs, Jolrael, Empress of Beasts, Meloku the Clouded Mirror, Panoptic Mirror, Kulrath Knight are some examples of this rare category: while being fine cards by themselves, they can create powerful effects when combined with a handful of right cards.
(2) is a complicated category, since we don't want the cards in this category to be just combo pieces. We want them to work decently in other decks. My approach was including a wide variety of effects in the cube. ajani's Pridemate, for example, is supported by all life gaining cards, some more strongly such as Soul Warden, Recumbent Bliss and Righteous Cause. Meloku combos with everything landfall (eg. Emeria Angel), the hideaway lands (eg. Shelldock Isle) and mass buffs (eg. Sunken City). Kulrath Knight turns Strength of the Tajuru into a mass Pacifism, works wonders with Serrated Arrows and so on. All these cards are quite good, but the combos are broken.
(5) might not be easy to figure as well. While simply looking for cards that do similar things to the pieces in (1), again we don't want to include narrow cards. Reanimation was a gift for Living Death deck, since it matters in pretty much any game, and interacts well with several other categories (discard, milling, removal). The best answers are frequently not obvious. Take Meloku for instance. No other card is going to bounce lands back to your hand AND create tokens. We can, however, include Squirrel Nest and Awakening Zone for one category and bounce lands, Vapor Snare, Gush, Khalni Gem for the other.