Goliath

Final boss of the first Shard/Island. You should reach him after about 6 hours of playtime. If you have trouble beating him just use a wood golems tornado to spin to win your way to the achievement. You are damage immune during it. Fire weapons work well against him but if you don't have one just use the best crafted one you got. Most of the bosses and mobs of this game can be cheesed as their AI is about as braindead as can be.