AMSI leverages the runtime, making signatures harder to identify and resolve. ThreatCheck also does not support certain file types such as PowerShell that AMSITrigger does.
AMSITrigger will leverage the AMSI engine and scan functions against a provided PowerShell script and report any specific sections of code it believes need to be alerted on.
AMSITrigger does provide a pre-compiled release on their GitHub and can also be found on the Desktop of the attached machine.
For our uses we only need to supply a file and the preferred format to report signatures.
amsitrigger.exe -i bypass.ps1