I've spent the last few days trying to figure out how to run a flow only when a message is posted with 'IMPORTANT!' and I just figured it out with the help of a few other articles. I didn't find anything else exactly like this, so I thought I'd share here. It's actually very simple.
Overall flow:
Click the menu for "When a new channel message is added..." and choose "Settings"
Find "Trigger Conditions" and click "Add"
Add the following
@equals(triggerOutputs()?['body/importance'], 'high')
Click "Save" and do whatever else you want with the flow.
It might take minutes for the flow to actaully work. I've seen other posts that indicate this can be slowed based on the number of API calls your tennant is making and your subsciption level. I've seen it take seconds and I've seen it take 20 minutes. ¯\_(ツ)_/¯
Enjoy!
