From the game's main menu, select single player or multiplayer, then "Scenario" as game type.
Be sure the game's difficulty is "Fearless". You can choose the difficulty while setting up the set of scenarios, or by pressing
anytime while you are in the set of scenarios itself to do a set "reroll".
The Powerup is a skill's upgrade that, well... power's up the skill itself with various effects such more damage or inflicting vulnerabilities to enemies.You use powerups by pressing , or to activate the corresponding powerup and spending Rage Points, or to activate the 3 powerups at the same time. See image belowThis achievement requires you to complete a scenario WITHOUT using any Powerups.
There isn't a scenario type that works better than others, so it's completely up to your playstyle. If you built a character heavily depending on Powerups damage, I'd personally suggest to avoid scenarios with time limits or domovoy escape (domovoy on fearless can be quite annoying to kill, due to the upgraded hit points, and they escape through portals more easily).
Once you successfully completed a scenario without using any powerups, the achievement will unlock.WARNING!1. Some people reported this achievement as "bugged": it didn't unlock even after meeting the described requirements
, unlocking later in the game while playing another scenario, or unlocking while meeting the requirements for another scenario achievement, such as2. If you are going for the "Monster Hunter Extraordinaire" achievement on your first playthroughI strongly suggest to AVOID playing scenarios until you actually completed the main storyline on Fearless difficulty
. The "Monster Hunter Extraordinaire" is known to be buggy in various ways and trying to complete the scenarios' achievements may void the MHE unlock.