I'm a Mage, so My Tanking Skills Are Useless!

I, the crispy mage, have been professionally outputting for thirty years. Once he traveled to a different world in the game, he awakened the tank skill tree. I got angry: "I'm a mage, how can I use these human shield skills?" Until one day, I casually put a shield on myself and resisted the devil's full blow. The Demon King was dumbfounded, his teammates were stunned, and I was the only one who fell into deep thought: "Wait... Something seems wrong. How can I, a mage, be better than a tank?" What's even more outrageous is that I discovered that these tank skills... Can actually hit critically? !