Hi HeavyGrinder,
Thanks for the report. There are couple things you can try to fix this issue:
1. If that still doesn't work and if you are using an Android device with 2GB or less RAM or iOS device with less than 1GB RAM, then try killing all other running apps before trying again.
2. Also, you can try reinstall the app incase the game cached a file that was corrupted during download. Please make sure you already have created an account so you can log back in after reinstall.
3. IF neither of above works, it could be your mobile device don't have the hardware requirement to load this stage. You can play the stage on your PC/Mac using the Bluestacks emulator if you have one:
https://www.bluestacks.com/Hope this helps,
Playmage Support