I want to make a system that detect when the variable (playerHealth) decreases, so it can indicate that you took damage. How do I detect when the variable changes? And more specifically, when the change is a decrease?
In the Events library, there's a hat block that runs when a specific variable changes.
While yes, it does only check for all changes, not just decreases, but you can easily edit the block to do that.
This hat block will only trigger when the variable decreases.
What/where's the event library?
In file 
> Libraries
Yes, that is better. I just modified the original block without trying to make it better.