What are Cores for and how does their rarity work?

Cores are what upgrade your dragons' Habits. Their rarity has to match the dragon's rarity:

• Rare Core 🔵 (blue) → upgrades the Habits of Rare dragons
• Epic Core 🟣 (purple) → Epic dragons
• Legendary Core 🟡 (gold) → Legendary dragons

A Core alone isn't enough: raising a Habit takes two materials together — a Core (rarity) + a Breedmark (breed).

Cores are permanent (they don't reset) and come from chests or the Market. Since a Legendary Core is useless on anything but a Legendary, keep them for the dragons you actually play — don't burn your top-end Cores on dragons you'll never field.