Trine 2
13 Achievements
3-4h
Dirty Tactics
Get at least 10 enemies killed by other enemies' actions in a single level
21.1%
How to unlock the Dirty Tactics achievement in Trine 2 - Definitive Guide
Just repeat until the ach unlocks. One lizard usually needs two hits of their fellow lizards to die, so to speed up the progress you can deliver a hit or freeze them first.
This is fairly simple, but alternatively you can use your shield for the knight and just block enemies in front of you, while another enemy comes up to attack.
This should be really easy for people with slow reflexes like myself.
Chapter 10 - Searock Castle
Play the level normaly, there's a lot of enemies spawning, so you have the chance that they will kill eachother during your playthrough. The level ends with a boss, Goblin King, who runs from the left to the right side of the room and there are goblins spawning all over the place. Just avoid the big fella by jumping and make him kill his own kind ten times - there you go.
There are a few ways to accomplish this. For location, you'll want to head to Chapter 6. You'll come to a part where you'll need to adjust some pipes to douse the fire that blocks your path. When you do this, a bubbling cauldron with red liquid in it to the right of the flames will spawn infinite enemies.
As the Wizard, you can simply levitate an enemy in front of you and other enemies will hack it down in an attempt to get to you. This requires an upgrade for the Wizard. You'll need to be quick in grabbing each successive enemy.
As the Thief, you'll want to purchase the frozen arrows. Freeze an enemy and then stand directly in front of it. As another enemy nears and readies an attack, jump out of the way and the enemy will shatter his buddy.
Whichever way you choose, the trophy will pop after the tenth enemy has been dispatched.
Co-Op Note: This trophy was a bit wonky in our co-op game. We had one person doing the work, but the three of us each received the trophy at different times.