Mordenkainen's Private Sanctum: Blocking Summoning Creatures into the Warded Area in Dungeons Dragons 5e

In Dungeons Dragons 5th Edition (5e), the Spellbook and Magic Items section includes several spells that can add layers of security to your adventuring party. One such spell, Mordenkainen's Private Sanctum, is particularly interesting in its interactions with other spells, especially Summon Creatures and Teleportation.

Understanding Mordenkainen's Private Sanctum

Mordenkainen's Private Sanctum is a 4th-level Abjuration spell with a casting time of 10 minutes and a duration of 24 hours. The spell creates a magical barrier around your chosen area that can measurably impact the way other spells function within it. Specifically, the spell defines several protections that apply to the warded area:

No sound can pass through the barrier at the edge of the warded area. The barrier of the warded area appears dark and foggy, preventing vision, even via darkvision. Sensors created by divination spells cannot appear inside the protected area or pass through the barrier at its perimeter. Creatures in the area cannot be targeted by divination spells. Nothing can teleport into or out of the warded area. Planar travel is blocked within the warded area.

These protections make the area a secure space, effectively restricting access from inward and outward spell-based manipulations.

Does Mordenkainen's Private Sanctum Block Summoning Creatures?

The central question here is whether Mordenkainen's Private Sanctum can block summoning creatures into the warded area. The spell explicitly states, 'Nothing can teleport into or out of the warded area. Planar travel is blocked within the warded area.' This exclusion clearly extends to summoning creatures, which inherently involve a form of planar or magical travel.

Furthermore, the spell's protection against divination also suggests that it prevents the tracking or location of your area, making the summoning process ineffective within the warded space. This aligns with the RAW (Rules as Written), which states that enchantment and illusion spells cannot affect creatures within the warded area, thereby preventing them from being targeted by such spells. As summoning involves the alteration of the target's existence and movement, it falls under the spell's limitations.

Practical Implications

The protection offered by Mordenkainen's Private Sanctum means that if you cast this spell to secure a camp or a base, you can be confident that no creature summoned by your party or their adversaries can enter. Even the demon-summoning rituals such as Summon Greater Demon would be ineffective due to the prohibition against teleportation and planar travel.

However, it's important to note that any creatures already present in the area when the spell is cast are not affected by the barrier. Once the spell is in effect, you have a 24-hour window during which the area is secured against teleports, spells, and other external manipulations.

Conclusion

In summary, Mordenkainen's Private Sanctum indeed blocks the summoning of creatures into the warded area in Dungeons Dragons 5e. This spell could prove invaluable for creating impregnable bastions or sanctuaries in your campaign, ensuring that your party's efforts in preparing the area are protected from external spell-based threats.