To capture a soul, at least one empty soul gem large enough to store that soul must be present in the inventory. Cast the Soul Trap spell on the target or assault it with a Soul Trap-enchanted weapon, then slaughter it before the effect expires. If you use a weapon enchanted with the trap component and kill the creature within the allotted time, it will also set loose any trapped souls. You can also collect souls while you're in combat if there are any available bodies. If you see someone dying near you, you can use their soul to trap another soul, increasing your maximum capacity by one. Trapping a soul gives you 10xp. At the end of each battle, you have a chance to find a number of treasure chests located throughout the battlefield. Opening these chests will yield items such as potions, armor, weapons, and shields that may help you in future battles. Chests contain items that can only be used once before they break or disappear. If a chest contains an item that could be used to trap more souls, you should open it to increase your capacity. As you travel around Skyrim, you will come across other ways to gain souls. Certain creatures, called "Dark Souls", will give you gold if you kill them. Dark Souls cannot be harmed by normal weapons so you will need magic to defeat them.