Peasant+ | ~500 Cards (trying to get back to ~400) | Graveyard-themed
A conspicuously synergistic discard and graveyard-based cube.
There's a lot of space for combining these themes. "Spells" will overlap with Madness, Looting/Cycling or Flashback themes, "Undergrowth" will usually overlap with Madness or Reanimator themes, and so on. Retrace decks, for example, combine Secrets of the Dead-style cards with retrace cards (Flame Jab) and land recursion (Groundskeeper) for the ultimate grindfest.
Color combinations can be also very flexible, as long as you get to see the right cards during a draft. There's very little stopping you from building a Reanimator deck, or an aggressive
Madness deck.