Soultrap is a spell that will trap a soul into a Soul Gem of sufficient size. In order for it to be used successfully, it must be cast upon a creature that is still alive, and the creature must be killed while the spell is active. You can tell the spell is active by the cloud of smoke that will circle the creature until the duration expires.
- By repeatedly using an item enchanted with Soul Trap on a creature that is going through its death animation, it is possible to Soul Trap the same creature to multiple soul gems. This is easily done with creatures like the Bull Netch.