The Witcher 2: Assassins of Kings
50 Achievements
1,000
50-60h
Torn Asunder!
Kill more than one opponent using a single exploding bomb.
15
How to unlock the Torn Asunder! achievement in The Witcher 2: Assassins of Kings - Definitive Guide
once you are in Flotsam, you can either buy grapeshot bombs from Cedric who is on the tree lookout just outside of the town(he will have a craftsman symbol on him) or buy the crafting diagram from him and make them yourself.
Then during the Quest: The Kayran: Ostmurk, you will have to go into a cave and get some herbs. Just make sure you have grapeshot bombs as you will be swarmed by NEKKERS. They are weak and will die instantly.
I got this on dark difficulty so it shouldnt be too hard.
Set fuse (press RB with bomb in quick slot) FIRE IN THE HOLE!
Achievement Unlocked
I found the best place to do this is above the graveyard on the path to the Kayrans Lair. Take out the bandit with the spear, then lower the health of the other two bandits to just under half way and have them chase you. If you're close together throw your bomb of choice and it should kill them both. The bomb that I recommend is the Grapeshot as it has quite a large blast radius and deals a fair amount of damage.
You might actually get this in the Prologue. You must have a bomb (grapeshot, Samum, etc.) equipped in your quickfire slots. Once the enemies are grouped together, throw it with . The bomb will likely damage multiple enemies, but it might not kill them. Keep throwing your bombs at the group and you will get the achievement.
Aforementioned above, you can actually get this in the prologue. At the end of the section where you hide from the dragon's breath in the wooden structures, you will be fighting two groups of knights in front of the gate. Throw bombs into the group here and you will almost definitely get it.
If you don't get it in the prologue, fear not. There are many more opportunities to get this throughout the game. Pretty much any area with a group of enemies will suffice.