Fast mode is not for stun+alch spells, it is ONLY for stunning spells, if you do fast mode with alch enabled, the timing will not be exact. So turn off fast mode, and it will work better.
Only use fast mode when you are not alching Although I will still post an update
I will optimize the code for vulnerability + alch spell, thanks for feedback
Update has been posted, version v0.78 is the latest update, please allow a few hours for update to be registered
Preview: (ignore version, it should say v0.78)