How to use magic (the signs) and traps in The Witcher 2 combat - Tutorial on the advanced combat techniques in The Witcher 2: Assassins of Kings.
Watch this tutorial in YouTube (720p HD): The Witcher 2 Tutorial - Advanced Combat Techniques - Magic Signs and Traps
Watch the combat basics tutorial : The Witcher 2 Tutorial - Combat Basics - Striking and Parrying
The Witcher 2 Signs & Magic
In The Witcher 2, Geralt has the knowledge of signs from the beginning.
Aard – a telekinetic wave that can throw back, knock down or stun an opponent. This sign can also be used to destroy obstacles, for example crumbling walls or stacks of barrels.
Igni – fire magic, throws flames that wound opponents & make gas (from bombs) explode. Upgraded Igni sign has a chance of incinerating opponents and also has a larger area of effect.
Yrden – a magical trap placed on the ground (wounds & immobilizes opponents when triggered). The sign's basic level allows you to place 1 yrden sign on the ground (With upgrade, up to 3 yrden signs at a time).
Quen – a protective shield that lasts for 30 seconds at the sign's basic level. It is a sign that Geralt uses on himself – quen absorbs all damage directed at Geralt, and the upgraded version reflects 50% of the damage back toward to enemy. While quen is in effect, Geralt cannot regenerate vigor.
Axii – charm an opponent. When the charm is successful, the enemy becomes an ally for a short while, fighting for you.
Heliotrop – not available immediately, needs points in the magic skill tree. The Heliotrop Sign creates a temporary immobile circular force-field area around Geralt, which considerably slows down everything inside the field except himself.
Reference: Sign, The Witcher Wiki
The Witcher 2 Traps
Clawer - Wounds and causes bleeding. Damage: 30 – 55
Rage - Causes foes to attack each other.
Biter - Wounds with shrapnel. Damage: 10 – 30
Talgar Winter - Slows foes down. Damage: 20 – 30
Conflagration - Incinerates foes and detonates other traps within range. Damage: 20 – 50
Snare - Wounds and causes bleeding. Damage: 30 – 50
Harpy trap - Effective against harpies.
Kayran trap - Effective against a kayran.
Nekker trap - Effective against nekkers.
Used trap - No longer usable
Reference: TW2 Traps, The Witcher Wiki