Not seen on screen, the spider has 18 hps left. However, you know that you just did about a quarter of the spiders total remaining hps. No matter if the spider was weak, or healthy, you know that about 3 more hits will finish it off. This is actually more information that you get with numerical damage.
Additional information can be supplied with pain skins that show visible damage on the spider. Or, the health glow of the targetted enemy may be visible on your screen. However, I would prefer the pain skin method.
