Most beginner deck-builders will tell you their deck "feels slow" or "stalls out" without being able to say why. The answer, nine times out of ten, is the mana curve.
What a curve actually is
Your mana curve is the count of cards at each mana value in your deck. A typical aggressive curve looks like:
| Cost | Count |
|---|---|
| 1 | 12 |
| 2 | 12 |
| 3 | 8 |
| 4 | 4 |
| 5+ | 0 |
| Lands | 24 |
A control curve looks completely different:
| Cost | Count |
|---|---|
| 1 | 4 |
| 2 | 8 |
| 3 | 6 |
| 4 | 6 |
| 5+ | 8 |
| Lands | 28 |
Both can win games. Mixing them, building a deck with aggressive top-end and control land counts, is how decks stall.
The failure modes
Three patterns account for most curve problems:
- Too top-heavy. You can't cast your big spells in time because you don't have the lands to support them. Symptom: dead five-mana cards in your opening hand.
- Top-heavy with not enough lands. You have the spells but can't develop the mana. Symptom: stuck on three lands while holding a six-mana finisher.
- Bottom-heavy with no late game. You curve out turns one through three, then top-deck three more two-drops while your opponent stabilizes. Symptom: winning the early game and losing anyway.
The fix
The classic heuristic is the 24-land rule: a sixty-card deck with an average mana cost around 2.5 wants 24 lands. Above 3.0, climb to 25–27. Above 3.5, you probably want ramp.
Lands are spells too. They're the spells that let your other spells happen.
Open any tournament-winning decklist and look at the curve before you look at the spells. The curve tells you what the deck is trying to do. The spells just fill in the details.