Ori and the Will of Wicks has a host of new bosses fighting against creatures of gigantic size compared to the protagonist of the game. In Moldwood Depths you will eventually come across a giant spider named Mora that you will have to fight. This boss fight also has a secret success.
How to unlock the Untouchable achievement
As with other locked secret achievements, you cannot read the description of that achievement until you unlock it. He is described as "defeating Mora without taking damage". Fairly self-explanatory.
For setup, this achievement is most easily obtained on Easy difficulty. It's possible on other difficulties, but you automatically deal a lot more damage on Easy, which will speed up the fight. If you've done a lot of exploring and leveling up, there are some shards that can make combat much easier, including Reckless which will increase your damage by 35% when fully upgraded and Spirit Bow has specific shards that allow you to reduce its damage from range.
When you meet Mora, she'll hit the ground beneath you and send you to an arena where the boss fight will take place. It's important to note that you can only damage Mora's head during combat. Starting the fight, she will hit you with her legs and hit the ground with her fangs which will launch a few poisoned projectiles on the ground. When she jumps into the air, she will send a shock wave through the arena floor when she lands.
After a bit, Mora will knock down the wall on the right side of the room. When this happens, the baby spiders will start to come out of the ground one by one and follow you across the room. Mora will also lower his head towards the ground and launch an attack that stays close to the ground, so make sure you're near a wall to grab when this happens. When Mora lifts her head back and screams, three baby spiders will come out of the ground and come after you. At half health, she will jump into the background and start hitting the ground. A shock wave will spread across the ground and rocks will fall from the ceiling. At this point, you need to use the Bash ability to start climbing the center of the room, and Mora will chase you into a new, darker room to fight.
In this new room, Mora will summon three more spiders to come and throw venom projectiles at you. When attacking you, she will be more aggressive and hit the ground several times. When she gets up in the air, she's about to spit out a beam attack that she'll move across the stage towards you. To avoid it, climb a wall to the top. When you lower Mora's health to around a quarter, she's howling and the room goes completely dark for the rest of the fight, so you'll want to activate the Flash ability.
If you manage to complete this fight without Mora touching you once, you will unlock the Untouchable achievement for 20 gamerscore.
