Is there any other way to check a variable constantly without using even tick?

right now im using a custom event to check a character health but in event tick but then it creating a problem that i cant play the montage that the character should play when the health hit 0

No in native way, UE4 is strongly tied to C++ which is quite low level and because CPU does not react to memory changes, there for it can not tell the program that variable changed and program is not only one who can change that variable (and even not CPU is only one that can do this) and engine it self cant really track that.

But this can be solved by programming policies and using encapsulation principle of object orientated programming. Make variable private (eye icon on variable shut down) and only accessible via get or set function, so other classes (blueprint or C++, but in case of C++ you can hack it) need to use those function to modify that variable, this way you can treat set function as make on variable modified event function as you force other code (Except class that variable is in) to use that function and other code can’t bypass that because you made varable private and you are 99% sure that that code will execute when variable is changed, engine code does that a lot.

Other more soft way is to make a function in class to do something and other code can call after can call then it’s update the variable, so action would be more optional.

There also

Like said, make it so only the getter and setter functions you write for that Blueprint class can change the variable, then in the function that sets it you can also have it signal other actors or objects that the variable changed, for example by calling an Event Dispatcher or some other way.

There should be no instance where you need to check something like that constantly. It should only be checked WHEN it needs changed, or read, etc…

But there ARE ways to do this. 's first sentence is wrong.