Anything You Can Do, I Can Do Better...

This achievement cannot be soloed — it requires at least two players, and one of them must be in a tank specialization (not just tank form, such as a druid in bear form without Guardian spec). Only a player in an actual tank spec can interact with the crystals.

When Feng the Accursed moves toward the first Mogu statue, two crystals appear: the one to the right (facing him from the entrance) offers Nullification Barrier, and the one to the left offers the ability that enables the mimicry mechanic central to this achievement.

The tank picks up the left crystal, which grants an extra button used to channel a link onto another player or pet — you cannot target yourself. Once the linked target takes damage from one of Feng's abilities, the button transforms into a reversal version of that ability, such as Reversal: Lightning Lash from his Lightning Lash attack, which you then use to mimic it.

You do not need to mimic every ability in a single winning attempt — progress can be spread across multiple successful kills of Feng the Accursed on Normal or Heroic difficulty.