Improve its habits
Why: each dragon has 5 passives; raising them strengthens it clearly — and it's permanent.
What helps directly
Habits
Gather a Mark + a Core to raise a habit
Each upgrade requires a Mark (tied to the breed) and a Core (of the dragon's rarity: blue, purple or gold). Gather them from chests, the Market or the shop.
WhereChests / Market / Shop
Related bonuses (good to know)
Stars (relics)
Unlock a locked habit
Some habits only open when the dragon gains stars: raise its stars to access them.
WhereDragon stars
Keywords
Other needs · Make a dragon stronger