As an expert in the field of gaming and lore, particularly in the context of fantasy settings where soul gems are often used as a mechanic, I can provide you with an informed answer.

In many fantasy games, a grand soul gem is a type of container used to capture and store the souls of powerful entities. The specific requirements to fill such a gem can vary depending on the game's universe and lore. However, generally speaking, a grand soul gem would be filled by capturing the soul of a particularly powerful creature, such as a high-level boss monster, a legendary beast, or even a significant character with a strong soul.

To fill a grand soul gem, one would typically need to:

1. Locate a creature or entity with a powerful soul.
2. Engage in combat or use a specific spell or ritual to capture the soul.
3. Use the grand soul gem as a vessel to contain the captured soul.

It's important to note that the act of capturing souls can often have moral and narrative implications within the game's story, and the use of soul gems may be subject to certain limitations or restrictions.

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Grand gems are only needed for Ghosts and Mammoths, making fighting these creatures desirable for the best enchantments. They can also be used to capture "special" enemies, such as the Dragon Priests. Dragon souls are consumed by the Dragonborn; you cannot soul trap Dragons.read more >>