Firewalker

Running barefoot across ember is not for you! You do it the elegant way. Yet, you're kind of drawn to fire and warm surroundings in general - you like it hot!

This achievement can be gotten by walking 1,000,000 tiles on fire while wearing Firewalker Boots. Note that any type of fire field will work for this achievement (even player-made ones) as long as the fields inflict damage for the boots to block.