Sigil Stones are magical objects that open portals between Nirn and Oblivion. The Sigil Stone is a necessary ingredient for the forging of Daedric armor and Daedra hearts at the Atronach Forge in The Midden beneath the College of Winterhold.
To obtain a sigil stone, the Dragonborn (after reaching a Conjuration level of 90 or higher) must seek out Phinis Gestor, an Expert Conjurer of the College of Winterhold. Phinis provides them with a summoning spell that calls forth an unbound dremora. Heading to the roof of the Hall of Attainment, the Dragonborn needs to cast the spell in a circle of candles. The dremora refuses to obey mortals' orders, and he must be defeated twice, after which he will submit to the Dragonborn's orders. Then, the Dragonborn demands that the dremora return to Oblivion and bring back a sigil stone. He obeys and the stone is acquired.
In exchange for the sigil stone, Phinis Gestor teaches the Dragonborn Flame Thrall, as well as now offering to sell other master-level Conjuration spells. The sigil stone will be returned to the Dragonborn after learning the new spell.
Once level 90 Conjuration is reached, a new dialogue option appears with Phinis Gestor: "What else is there to be learned about Conjuration magic?" He mentions that, in order to give any higher-level Conjuration spells, he must have a sigil stone from an Oblivion gate. He then teaches the Summon Unbound Dremora spell. He tells the Dragonborn to climb up to the roof of the Hall of Attainment, use the spell, then defeat the summoned, unbound dremora.
This section contains bugs related to Sigil Stone (Skyrim). Before adding a bug to this list, consider the following:
- Sometimes the dremora becomes untargetable. This means he is unable to be banished or killed, permanently disrupting the quest.
- One fix is to reload to before the quest and try again.
- A work around would be to use the Unrelenting Force shout to knock him off the outer side of the college walls, using the fall to kill him.
- Sometimes the floor in the training part of the college will be glitched open and a chest will have that and other valuables.
- It is possible to receive a second sigil stone. If the stone is placed in the Atronach Forge immediately after receiving it, when talking to Phinis, he will take nothing out of inventory but return another sigil stone when completing the quest. The second sigil stone is effectively useless though.
- If the dialogue before fighting the dremora is skipped he can't be summoned again.
- The dremora will sometimes reappear after the quest is completed, and be untargetable. However, if a follower is ordered to attack, the dremora will turn against you. If this happens, neither the Dragonborn nor their follower can deal damage to the dremora, however he can damage them. Also, the dremora is nearly impossible to evade.
- The sigil stone can also be found in a secret chest in the college. This secret chest is located in the Hall of the Elements in the outside ring, and is only reachable by using the off map glitch. Getting inside the chest requires jumping and while falling, clicking the chest as it goes by. After looking inside it, the fall continues, but the Dragonborn shall be teleported back to the position from which they jumped with all the obtained items from the chest in inventory.