My first post on these forums... /waves at everyone
Unfortunately, you will find that many mobs in WoW have powers (abilities) beyond those of players. Jsut to pull a rabbit out of the hat here: on the Succubus quest, the Voidwalkers and Imps have to be killed seperately -- they don't die when their Master dies, as a player's familiar does. And Elites, using another example: not only are they some level, say lvl 20 for this discussion, they have extraordinary abilities and staying power that no other comparable level mob (or player, for that matter) has; that's why they call them Elites...
So, get used to the odds being stacked in the mob's favor in many, many cases. Expect it going into fights and you'll rarely be surprised when it happens. On the other hand, when you go up against a
softie mob, count your blessings and whack away!
Cheers!
Ci