Wasn't Even Close is a grandmaster combat achievement which requires the player to kill TzKal-Zuk without falling below 50 hitpoints at any point during the Inferno run.
All waves will need to be dealt with cautiously, as all of the Inferno monsters hit very hard and the later waves will consist of multiple monsters that use different combat styles, which can easily combo the player out if their attacks aren't protected against.
During the fight against Zuk, the strain is not as intense as in the previous waves, until it is at 20% health when the Jal-MejJaks appear. Caution is required due to their retaliation AoE attack, which can deal up to 10 damage in a 3x3 area. As four of them spawn and the player is continually hit by them while moving with the floating shield, it is recommended to kill them as quickly as possible while also eating as much as possible.