You can lure an Epic into another Epic. Note: Save your game before you get the battle with the Epics. An Epic creature is much bigger than the usual species. It can one-shot almost anything even though its attack range of 3-7 is not very powerful to you. Epic creatures have 1,000 health. First, get a Spit weapon with at least 4+ Spit. Spit will lure the Epic towards you but do not die. After that, have two or three Pack members (Rogue recommended). Rogues are more powerful than a normal creature, but weaker than an Epic. Rogues have 250 health and do massive damage. Spit at an Epic creature and make it follow you. Stay at a distance and lure it to another. Find the two you want to battle. Once they start, find the one that will probably win. Start attacking the one that is about to win. This will raise your chances of getting the achievement. Once the Epic battle is over, the Epic that won and the one you attacked should be about down to 200 health or less. If not, quit to the main menu and restart. Constantly Spit until it is down to less than 10 health. Charge it, then Strike or Bite to win and get the "Epic Killer" achievement.