this is good if you can get inside his guard but generally you hafto soften him up before you get a chance to knee him or else he might not let you grab him. As an example when you grab him he might just slap you across the face really hard before you have even thrown one strike. And knees are good but they arent necessarily "brutal" they are just one of the effective techniques. if you just throw a typical knee to the face without any other techniques they arent TOO hard to block. Depends if it comes in straight like to the thigh or in an upward motion. You can typically block a knee by crossing your arms and braciong your forearms against it. If you have a pseudo down x block you can counter it pretty easily by looping your outside arm under his leg and front arm pushing against his chest and throw him. If you are the guy kneeing if the guy blocks before you set your leg down from being blocked you can just throw a vertical elbow to his face.
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