This is a fairly simple achievement but it can take a bit to finally achieve. You have to take 10,000 damage as the elf which is a bit cumbersome given that the Elf has only 64 hp. You would have to die approximately 156 times to achieve this. There are several ways to achieve this:
1) You can just play the game and let it happen when it happens.
2) Load up any level with a trap right off the start, walk into it, die, reload and repeat.
3) During your kill grind allow the enemies to kill you as you will gain a considerable amount of skull coins during the process and use food to heal to maximize the damage done.