What is Tier 10 at the end of a Reign and why does it matter?

Tier 10 is the campaign's central requirement: you must reach Stronghold Tier 10 before the Reign ends to be able to finish the "Heirs of the Dragon" campaign (11 chapters plus an epilogue).

Why it matters:

• Without Stronghold Tier 10 you get stuck on the last chapters and miss the epilogue and its final rewards.
• The Stronghold climb takes time (resources plus build time), so it can't be salvaged in 2 days.

The plan:

• Aim for Tier 10 well before the Reign's deadline.
• Use the Upgrade Stronghold event to push your tiers and collect rewards at the same time.
• Keep resources and speed-ups in reserve for the last tiers, which are the most expensive.

It's the structuring goal of your whole Reign: plan your progression around it.