Dragon's Dogma: Dark Arisen

There are many different combinations for this, but the easiest is to simply fill a lantern with oil. You'll find Flask of Oil often, or can use an Empty Flask and fill it by finding a jug of oil around towns. Select the lantern in your inventory and choose "Combine" and then a list of acceptable items (the Flask of Oil) will appear. Select that and the lantern will fill, unlocking the achievement.