The Witcher 2: Assassins of Kings

This achievement is achieved by mutating five of your abilities with mutagens which you can acquire from looting monsters or making potions if you have the Side Effect ability from the alchemy skill tree.The real troublesome part about this is that only certain abilities can be mutated and they are usually located near the end of a skill tree.

The list of abilities are as follows.

Alchemy tree - Berserker
Condensation
Metathesis
Amplification
Mutant

Magic tree - Advanced Yrden Sign
Sense of Magic
Control of the Power

Swordsmanship tree - Invincible
Combat Acumen
Whirlwind

Training tree - Fortitude
Arrow Redirection

Also note that each ability can only be mutated once so if you are doing a legit play through and not just rushing for the achievements make sure only to use greater mutagens. Two of the best mutagens don't have a greater version but are quite powerful are the Madness Mutagen and the Enhancement Mutagen.

I would also like to note that a great place to acquire mutagens is from Harpies in chapter two especially if you are hunting the Madness Mutagen. Below is a link to the Butcher of Blaviken achievement guide by Wyndo which directs you to a place with infinite spawning harpies.