Meat Shield

If someone gets attacked and you are within 5 feet from them, you can use your reaction to jump in front of them to deflect the blow. This decision must be made before the roll is called.
Upon calling, your character will give the targeted character 3/4 cover, or +5 to their AC. If the attack would still hit them, it still hits and your character will take 1/2 damage. If it does not hit the targeted character, the DM will roll another d20 to see if it hits your character for a full blow or misses entirely.