Does it multiply your max HP (the one with and additional HP from skill and items buffs) or just base HP (base HP stats)?
Your HP after buff = Your current HP x 2 + (additional from Rune’s attribute) 
Does it multiply your max HP (the one with and additional HP from skill and items buffs) or just base HP (base HP stats)?
Your HP after buff = Your current HP x 2 + (additional from Rune’s attribute)