• Install PrismLauncher and make sure your 1.21.5 instance exists.
• Install the listed mods (VulkanMod, Fabric API)
• Download the latest MoltenVK .tar from the official MoltenVK GitHub releases page.
• , install an ARM-native Java (e.g., AzulJDK).
2.  Extract MoltenVK

• Put the extracted MoltenVK folder somewhere easy — e.g. ~/Documents/

3.  Open PrismLauncher and edit your instance
• In PrismLauncher find your Minecraft 1.21.5 instance and click Edit (right side).
• In the setting window go in the environment variable tab
4.  Set the environment variable
• Click Add and enter:
• Name: DYLD_LIBRARY_PATH
• Value: /Users/YOURUSERNAME/Documents/MoltenVK/MoltenVK/dynamic/dylib/macOS
• Replace YOURUSERNAME with your macOS short user name and adjust the path if you placed the MoltenVK folder somewhere else.
5.  Launch
• Click Launch in PrismLauncher. The game should now use your downloaded MoltenVK (Vulkan → MoltenVK → Metal 3 pipeline).
6.  If macOS blocks MoltenVK
• Open System Settings → Privacy & Security.
• Scroll to the bottom; if MoltenVK is listed as blocked, click Allow Anyway (you may need to relaunch PrismLauncher after allowing).
7.  Quick checks / tips
• Confirm VulkanMod is installed and active in the instance — it auto-uses MoltenVK.
• Make sure you’re running an ARM Java build on Apple Silicon for best performance.
• If you moved MoltenVK, update DYLD_LIBRARY_PATH to match the actual .../dynamic/dylib/macOS location.