A thing block the EnderDragon

At the End, a thing like the portal after the Enderdragon was here, but without the portal and the egg. The Enderdragon go to it and block when he touch it. When he are blocked, the EnderDragon don't move but can attack without move and the arrows don't touch him. When we hit him, he don't move. When we break it, (the thing) the dragon block again in the hole. When he are blocked, we can attack the dragon with swords.