So I tried it the other way:
1. Before installing the 10.13.6 combo update, boot into Volume "macOS" and terminal this: sudo nano -W /System/Library/CoreServices/SystemVersion.plist
2. Change both "10.13.3" string into "10.13.6", leave "17D47" alone, no need to change that.
3. Reboot, then install Xcode 10.1, run it and let it finish installing components, if it don't let you run, reboot and retry.
4. Uninstall the web driver, and undo the change in step 2, reboot your computer.
5. Boot into Volume "Clone", install the 10.13.6 combo update and security update 2018-002.
6. follow shaneee's tutorial, replace stuffs, terminal rp, terminal kextcache -i/-u. and if kextcache -i don't work as expected like return some error code, try this:
6.1 Download "Shaneee_10.13.6.zip" from Shaneee's github: https://github.com/Shaneee92/AMD-High-S ... U/releases
6.2 Plugin the USB driver "HighSirraAMD", which is the one used to install 10.13.3 V3 Unofficial.
6.3 Unzip "Shaneee_10.13.6.zip", replace the files with the same names in HighSirraAMD/AMD, remember to make backups. (actually i don't know the files replacing is necessary or not, i did it tho.)
6.4 Reboot and boot into USB HighSirraAMD, ternimal "amd".
7. boot into Volume "macOS", see if it works.