Why do my bonuses disappear at the start of a new Reign?

Several things reset at the Reign change, which feels like "losing everything" — but it's normal:

• Your dragon level goes back to zero → re-raise it through combat/Meat.
• Your buildings and research (Dragon Care, War Tactics, Infrastructure) have to be redone → your stat/damage bonuses start low again.
• Your House Level resets → and it's House Level that activates your Heirloom buffs.

The key point about Heirlooms: the upgrades stay unlocked (permanent), but they're only active if your House Level is high enough. So early in a season, re-grind House Level first (daily login + chapter quests + events) to switch back on buffs you've already paid for.

What hasn't moved: your stars, Habits, Relics and gold.