Here is the full list of all 45 Underworld Ascendant achievements.
Killed several enemies without being detected.
Killed an enemy without being detected.
Used Wall Run off a free object.
The world is your playground.
Killed an enemy with a tripwire.
Caused multiple enemies to be killed by physics damage.
Because the darkness should fear you.
Defeated a Ripper.
Pounced on an enemy.
Hid in a Deep Slug smoke trail.
Feed a Deep Slug one of it's favorite foods.
Caused an enemy to be killed by physics damage.
Gathered a key item without being detected.
Resolved multiple quest objectives undetected.
Enemies convinced to turn on each other.
A good fighter knows when to Parry.
Leap Boldly Ascendant.
Switched a lever without touching it
Resolved a combat encounter against multiple opponents who detected me without taking damage.
Killed an enemy with spells.
Defeated an enemy without being damaged.
Blocked an arrow with a held object.
Snuck by initial foes without being detected.
A Mind Crippler was killed indirectly.
Jumped on a levitated box
Balanced on a plank.
Reflected projectile.
Caused an enemy to investigate a sound.
Killed an enemy with a trap.
Killed an enemy with a burning crate.
Jammed a trap with an object.
Killed an enemy using a Deep Slug trail.
Caused a creature to investigate a sound, but was undetected.
Successfully casted a spell with two runestones.
Successfully casted a spell with four runestones.
Caused an enemy to be killed by Fire.
Caused multiple enemies to be killed by Fire.
Dispatched an enemy who was bound while time was slowed.
Bound or stuck in place a creature, who was then dispatched by a trap device.
Killed multiple enemies with traps.
Rebranded a wand with a new spell.
Regained a massive amount of health using Arcane Regeneration.
Used "Merciful Fate" to cheat death.
The Saurians passed this technique down for generations.
Performed a combo attack with a sword, axe, or without a weapon.