Accomplish the indicated achievement to get the corresponding number of Gamerscore points:

Fright (25 points): Acquire the Scythe of Imperial Massacre.
Soul Grabber (20 points): Collect 10,000 souls.
Soul Reaper (20 points): Collect 100,000 souls.
Legendary Executioner (40 points): Beat the game on Witchslayer.
The Witch's Ultimate Weapon (30 points): Acquire Spirit Cannon.
Terror (20 points): Acquire the Scythe of the Assassin Queen.
Ring Around the Rosie (20 points): Catch and defeat five enemies at oncewith Mag Mell's Rose.
Keeping Healthy (20 points): Collect 100 Recovery Items.
Souls United (20 points): Defeat 200 enemies with Knight's Fury.
Combo Master (20 points): Attain the highest possible combo rating.
The Sonic Knight (20 points): Perform a 30-hit combo.
Take One for the Team (20 points): Perform 10 counterattacks while takingenemy attacks.
Master Executioner (30 points): Beat the game on Hexen Knight.
Until Next Time... (20 points): Force Faust to retreat.
Storm Stopper (20 points): Defeat the witch Trendula.
Hair Cutter (20 points): Defeat the witch Rapunzel.
Bone Collector (20 points): Defeat the witch Straeggele.
Ice Breaker (20 points): Defeat the witch Trude.
Fire Fighter (20 points): Defeat the witch Holda.
Novice Executioner (10 points): Beat the game on Page.
Average Executioner (15 points): Beat the game on Squire.
Skilled Executioner (20 points): Beat the game on Knight.
Stone Crusher (20 points): Defeat the witch Verderinde.
To the Fires of Hell (20 points): Defeat Faust.
Nice Try! (20 points): Repel an enemy's attack 10 times.
'Tis But a Scratch! (15 points): Experience your first revival.
It's Just a Flesh Wound! (20 points): Revive 50 times.
Elegantly Executed (20 points): Land 100 Perfect Finishers.
Head Bangin' (20 points): Bash the same enemy into a wall five times.
Get 'Em Up (20 points): Pick up the same enemy five times.
I'm Taking You With Me (15 points): Damage both yourself and an enemy with Witchcraft.
Careful With That! (20 points): Damage both yourself and an enemy with Witchcraft 10 times.
Touch Too Much (20 points): Carry Gretchen around for a long time.
Bodyguard (15 points): Save Gretchen from enemy attack.
Guardian Knight (20 points): Save Gretchen from enemy attack 50 times.
Eye Candy (20 points): Use Witch's Embrace when no enemies are present.
Expertly Executed (20 points): Land 1,000 Finishers.
Witchcraft Collector (20 points): Acquire all Witchcraft.
The Finer Things (20 points): Acquire all equipment.
Light Reading (15 points): Acquire a collection item.
Her True Strength (20 points): Defeat 200 enemies with Witch's Embrace.
A Worthy Apprentice (20 points): Defeat 50 enemies with the help of Minukelsus.
Growing Power (20 points): Upgrade a Witchcraft.
Bloody Massacre (25 points): Defeat 1,000 enemies.
Executed (15 points): Land a Finisher.
Skillfully Executed (15 points): Land 100 Finishers.
Information Junkie (20 points): Acquire all collection items.
Blood Spilled (15 points): Defeat an enemy.
Blood Bath (20 points): Defeat 100 enemies.

Additionally, there is one secret achievement:

True Peace at Last (20 points): Defeat your true enemy.