Trigger on reply from the requester

Hi Eric Lau welcome to our Community! 

When your requester replied to the tickets, the ticket status is set to open automatically by default. 

You can maybe use the conditions Ticket is Updated, Current user is enduser where the current user is the type of user that last updated the ticket:

I hope this helps! If this is not what you're looking for, feel free to reach us via Messaging so you can provide your specific use case and we can recommend something for you :) Thanks Eric!

Quick related question: is the condition current user defined as the user who triggered the trigger?

Is (end-user) the requester as well?

Thanks for the welcome.

Hi Eric Lau the current user is not necessarily the requester, the current user in the condition refers to the last person who updated the ticket. 

So if we're referring to the conditions ticket is updated and current user is the end user, it should be defined as the person who fired the trigger :)