I do have a solution that's similar to PRS Sarg up there. However instead of picking Apollo (assuming you're just starting out in the game with only the starter characters) you can buy Artemis for a relatively low favor price, she was one of the first I bought. Now buy the passive boosts in game where attack speed is listed as a boost. Now I had a good chunk of them and she has her Vengeful Assault attack (
) which speeds up her attacks. Now if done correctly and you have at least 2.1x attack speed and use that attack you'll unlock the achievement once you attack.