Using x64dbg to trace the decryption routines. The challenge often requires "dumping" decrypted buffers from memory for further inspection.
"7xisHeadTrick.zip" refers to a high-profile originally featured in the Flare-On 7 Reverse Engineering Challenge (2020) . Specifically, it was Challenge #10, designed by the Mandiant (formerly FireEye) FLARE team to test advanced de-obfuscation and architectural knowledge. The Core Challenge 7xisHeadTrick.zip
A "good" write-up for this challenge typically follows these stages: Using x64dbg to trace the decryption routines
Mandiant usually publishes a PDF with the intended solution path for every challenge. it was Challenge #10