Tripwire

Tripwires are some of the oldest traps known to man. And in the Dragon Age they are used a lot. You can find them in many of the dungeons around Ferelden. Simply pulling the string will set off an effect, it might be a balista firing or a barrel exploding or just plain damage to one of the companions.

It's possible to detect these traps with enough awareness and to disarm them with enough skill as Rogue (Deft Hands). Disarming them is a rewarding business, not only will your party be safe. You will also gain valuable experience. For most tripwires between 5 and 50 XP. The more XP you get the higher your skill has to be to disarm them.