This Feat can be acquired in its corresponding campaign by finishing any stage without taking damage, including from its boss.
Are excluded encounters, loot stages or Relic and Arcana challenges. In the case of Specter of Torment, the memories stages are also excluded.
The best stage for this Feat in each campaign is the Plains as it is shorter than most stages, has easy enemies to dodge or kill and its boss (Black Knight) is one of the easiest to defeat.
However, players may try to complete this along with Untouched. In this case for Specter Knight, King Knight might be an easy option.