i was on the terrace outside my bedroom of my castle, and all the way across the prarie, i saw a little boner in front of my mine. so i climbed the ladder up on my roof, and i shot for the sky. it landed, caught that ***** on fire, (it was enchanted) and he ran around in circles and i shot him again. pwn.
it helps to 1-hit him, so drink some strength potions and use enchants.
I know what i'm doing. Gravity is not a problem for me. Bows have a slight inaccuracy when shot. It may go a bit to the left, or a bit to the right, up, down, or anywhere in between. Nothing you can do about it.
Makes it more realistic, don't you think? You're not gonna get a perfect shot every time you shoot in real life.
I have gotten the achievement before though it is very difficult to get. It is not impossible to get though. It took me a while to get though after some practice with the bow and tons of mobs for targets, I manged to get the achievement.