Combo

Combo decks use the interaction of two or more cards (a "combination") to create a powerful effect that either wins the game immediately or produces an overwhelming advantage. Combo decks value consistency, speed, and resilience: the deck should be reliable enough to produce the combo on a regular basis, the deck should be able to use the combo fast enough to win before the opponent, and the deck should be able to withstand disruption and still win.
Many decks have smaller, combo-like interactions between their cards, which is better described as synergy.