I am using a Elf Swordmage at the moment, and have given him a feat called
Rose King's Shield
Prerequisite: Avenger or Swordmage, proficiency with longsword
Benefit: You gain a +2 feat bonus to Endurance checks. Once per turn when you hit an enemy with an attack power associated with this feat while using a longsword, you gain 5 temporary hit points. If you ended your turn more than 2 squares away from where you started, you instead gain 10 temporary hit points.
Associated Powers: Booming Blade, Focused Fury
My question is, do these temp hit points stack during an encounter? i.e. if you hit someone with that associated power several times.