Procedure help please

Hey, I'm fairly new to coding and I'm struggling with an idea I have for a mod that I'm making, 

I want to make a item a player eats that once eaten they'll gain potion effects what I have done but after a set time I would then want them to die as it's a kind of boost of power but after a set time they die, I've tried different combinations I thought would work and I have no idea where to go with it from here. I've sent pictures below to kind of explain what I've done.

https://gyazo.com/68a1b9d8b451fb860a796d4cd7c5b224