Mercenary: Ethereal

 is a challenge in Risk of Rain 2. It is completed as by completing a Prismatic Trial without falling below 100% health.

Losing any health or shield invalidates the challenge. Losing barriers (for example, from ) does not invalidate it.

Tips

 * Try to destroy time crystals by reducing their health enough for or  to destroy them, so that no damage is incurred from the resulting explosion.
 * Drones and turrets can serve as distractions for enemies, allowing one to use Blinding Assault or Eviscerate to either finish off or soften enemies without risking being hit.
 * All interactables spawn in the exact same location when restarting the Trial, making it useful for finding drones and turrets to help distract and kill enemies.
 * Items in chests are static in the trial, meaning the spawned item from a certain chest or Lunar Pod will never change when retrying a trial. This is useful for finding items that increase the player's damage (,, etc.) or add effects that help them flee (, , etc.) without having to worry about the item being different.
 * Ranged attacks are especially useful. Items like a or a  can improve the chances of success. However, this is limited by the generated seed that keeps item spawns static.
 * Shaped Glass does not invalidate the challenge as it is not technically falling below 100% health. Rather, the 100% health value is reduced. The double damage can prove extremely useful; taking any damage fails the challenge anyway, so there are no downsides to doing this other than the lunar coin cost per attempt.
 * Runs will have random artifacts active for the generated seed. and/or  are recommended for doing Ethereal due to controlled selection of items and the 500% damage increase, respectively.
 * Obtaining the allows the player to engage enemies at long range with relative safety. However, without an extremely lucky Lunar Pod, this option is not available until reaching the  and cannot be used on the first stage in the Prismatic Trial.
 * Obtaining a makes this strategy even more effective, at the cost of chance effects.
 * The cost Mercenary a crowd-control attack, but afford him a powerful retreat option that gives total invulnerability.
 * In Prismatic Trials, going through Bulwark's Ambry's portal causes the trial to end, granting the player victory and the achievement. If Sky Meadow is the first or second stage in trial, this is an easy way to skip a stage.
 * The is especially useful for this challenge to make short work of the Teleporter Boss.
 * If the is enabled, Void Seeds will spawn caches rather than cradles. This can allow one to obtain the very useful  without having to sacrifice half their health to do so.
 * This can be very difficult to pull off in practice, however, as any s can be tricky to clear without taking damage from the fog.