I recommend increasing the intensity of your igni ability and light an opponent (wolves and humans were most common and easy to light in my opinion) on fire BEFORE you throw the dragon dream bomb in their direction, so as not to waste a bomb. You'll know you've done it correctly because you'll see the bomb engulf a larger area in flames when tripped. Some achievements are glitched and may require more than 10 times done correctly but it will unlock, congrats in advance.