User blog comment:Fistful of Force/Fistful of Force's Tanking Guide/@comment-3360527-20110810032350/@comment-3565549-20110810044906

Actually, there is. There are two, the first literal, the second, realistic. Firstly, Armor reduces damage on a reducing scale, so one point in armor at when you have 99 armor gives more reduction than when you have 200. Secondly, while you could become unkillable, it's not useful, because you can't actually DO anything beside stand there. It's much better to be "Very hard to kill, but doing some damage and disruptive".