Fortnite Battle Royale - Secret Battle Pass Tier Location Guide (#1 Blockbuster Challenge).
Secret Battle Pass Tier Location Guide
When you complete the Blockbuster challenges in Season 4, you will get a new loading screen. In the loading screen, there is a battle pass tier shown. Go to the location shown and you'll see the secret battle pass tier (10 stars) waiting to be collected.
Note: This only spawns if you've complete the #1 challenge in the Blockbuster Challenge.