It's an Actor that has Pin To Screen on, and put into the upper corner of every room I want it to appear in.
Then under the On Update tab, I have it constantly checking what number the Health Variable is on. Whenever the player is hit by an enemy, I add one to the Variable and have the life counter go down.
If the Variable gets to like, four for example, then the player is teleported to the game over screen via the map.