Tweet of the Day: Is This Thing Still On?
Want to create a near invincible enemy? One that survives everything the protagonist throw at them? You could give them strong armor, great speed, or a devastating form of attack. Or you can give the an Adaptive Ability. This time of opponent can adapt to any attack making it difficult to destroy by sheer force alone. But this is also the kind of enemy that brings out the best in guile heroes, who will have to come up with ways to either bypass the the enemies defenses or neutralize the threat in an imaginative way.
The problem with this is of course that the author solution to the problem of their own creation may not be as clever as they think they are and come up with an implausible, silly, or unsatisfactory (to the audience at least) way of dealing with the threat.