Two things.
First please check with a “Print String” if “Event Any Damage” is receiving any input at all.
And secondly look in your spike settings if it does fire “Overlap” events. There is a setting for each part where you can set if it should or should not do so meaning it can potentially just not fire at all. (While you’re at it check this for your character as well. Better safe than sorry 
This is basically the correct way to do it though. However you might want to subtract the HP before checking because right now it is possible (if the character gets more than 1 damage) that he has negative HP… which is not really ideal to say the least ;D