Which Habit should you upgrade first on a dragon?

Prioritise the set Habits ⭐ and the 5th Habit:

• The 5th Habit is the strongest one on every dragon (the Habit Growth event confirms it pays more than the others).
• Set Habits ⭐ (the ones that read "[Order] grants") reinforce the dragon's active Order: they multiply what its command already does instead of adding a small isolated bonus.

Another smart angle: Habits that lower an enemy defensive stat (Instinct / Initiative / Intelligence) are team multipliers — they lift your whole army, not just one dragon. Concentrate your Legendary Cores on the Legendaries you actually field instead of spreading them thin.