How does the Upgrade Stronghold event work?

The Upgrade Stronghold event rewards you for raising your Stronghold tier and your buildings. Each upgrade gives points that unlock reward tiers.

As with "Spend Gold/Resources", it's all about timing: upgrading a building or passing a Stronghold tier is part of your normal progression, so you may as well do it during this event to collect the bonus rewards.

Two things to know:

• Passing a Stronghold tier is what pays the most points — keep a big upgrade in reserve.
• The campaign requires Stronghold Tier 10 before the Reign ends, so using this event to push your Stronghold kills two birds with one stone (campaign objective + event rewards).

Prepare your resources in advance so you can chain upgrades the moment the event starts.