Help with loop

I'm trying to make a procedure that when entity attacked will repeatedly get a value (coinValue) for 2 different players (source and event entity) and keep getting those values to change another value of the 2 players (coinAmount) and have it stop repeating this until 1 player hits 0 on coinAmount. I've tried to use a while loop to make this work but it never works no matter what i try, (it usually just crashes). I don't believe that using a seperate procedure with a tick update trigger would work either because i need to use the source and event entities. If anyone has any ideas, please share them :)  Imgur Link

if anything else needs to be clarified lemme know