The Witcher 2: Assassins of Kings

Chapter 1

Nekkers - grapeshot bombs req. to destroy the 4 nests.
Endrega - destroy the cocoons to draw out the queen. 2 sets of 3 cocoons for 2 queens.

Chapter 2

Roche - Rotfeind - burn all 9 corpses
Iorweth - Harpy - use Harpy Traps to destroy the nests, 4 in the quarry and 3 in the harpy lair during the Hunting Magic quest

Chapter 3

Gargoyle - destroy the 3 seals, each seal is a room with 4 runes and a treasure box, you must extinguish the rune in the correct order. Read the 4 Rune of Power books the get a description of the runes.

The 4 runes are Animal - Death - Sky - Time

Animal - snake creeping along a riverbed (looks like a Z on its side with _ above and below it)

Death - a scythe (looks like a large 7 with a small backwards 7 on the lower left edge)

Sky - a line within a parallelogram (looks like a box with a diagonal line from the lower left to upper right)

Time - an open hourglass (looks like an hourglass with the top cut off /or a sharp angled jesus fish)

each room has only 2 possible solutions

Room 1 poem (southern)
A Doe's long shadow... (Solution - animal, sky, death, time)
or
Three field mice... (Solution - animal, death, time, sky)

Room 2 poem (northern)
Glittering fish... (Solution - animal, time, death, sky)
or
Behold the comet... (Solution - sky, animal, time, death)

Room 3 poem (amphitheater)
Divertimento!... (Solution - death, sky, animal, time)
or
On the dark sky... (Solution - sky, death, animal, time)

There are 4 quests in the game you need to complete for this achievement. These quests are found on the notice board. In the main town in each chapter.

In Chapter 1:
Do the nekker (requires grapeshot bombs) and endrega quests.

Chapter 2 Roche:
Do the rotfiend quest.

Chapter 2 Ivoreth:
Do the harpy quest

Chapter 3:
Kill the gargoyles. (You must complete the quest by disabling all the runes, you cannot just kill all the gargoyles.)

For the gargoyle quest, you must disable the runes in a certain order. There are 4 runes. Art/Beauty, Sky, Time, and Animals. Read the hints in each room and match them to each rune. Example: "Behold the comet/ It is like a wolf in times of scarceness/ An evil lullaby"

Means: Sky - Animal - Time - Art/Beauty

The achievement has been known to unlock early during the gargoyle quest but is random and you still need to do all the other quests before it.

There's a glitch to skip the Gargoyle contract in Chapter 3.

-Complete the Nekker and Endrega contracts in Chapter 1.
-Complete either the Harpy or Rotfiend Contract in Chapter 2 depending on who you sided with.
-Accept the Gargoyle contract from the notice board BEFORE going to the end (meet Roche or Iorveth at the ampitheater). Achievement will pop after the ampitheater cutscene and before you run up the stairs to fight the dragon.

You must have the quest in your quest log in order to trigger the glitch, which counts the quest as completed for some reason even though it fails. It did not work for me the first time I tried without accepting the contract.

Saves a lot of time since the final contract is long and a pain in the ass.