Why is the dragon called the heart of the army in Dragonfire?

An army is 1 dragon (up to 3, in fact) plus troops. But the dragon leads: its stats, its abilities and its auras decide how the fight goes.

Troops are mostly fuel: when a dragon runs out of troops it's forced to retreat. They make you last, but they aren't what creates the strategic difference.

What makes a dragon strong:

• Its 4 stats (Strength, Instinct, Intelligence, Initiative).
• Its breed (Champion, Warrior, Hunter, Sentinel) and its role.
• Its Order (its special ability) and its Habits.
• Its Star Rank, which unlocks stronger versions of those abilities.

So, as a general rule: pick your dragons first, the troop type comes after.