Custom attack patterns for mobs

Hello, i am trying to make some custom attacks for my entity but can't quite get it to work. I am currently trying to use the "on entity tick" trigger without success. I tried using a "wait x ticks" followed by a lightning strike and an explosion, but for some reason it repeated the attack like 100 times in rapid succession. Should i use another trigger, or did i simply mess up?

EDIT:On second thought i think i can kinda tell what the problem was. I think it was starting the code every tick and as such it struck lighting after the time interval for every tick. Is there any way to fix this or an alternative?