Demolish the Portal of Hermes
Solomonic Alchemy 25
Alteration: Major
This spell greatly diminishes the cohesive property of the physical structure of a Portal of Hermes, making it structurally weak enough to be destroyed with a simple strike. Since enchanted items are much more durable than mundane items, the alteration must be Major.
(Base 10, +3 Major)
Since this spell is likely cast under an aegis, the caster must somehow have a high enough casting total (or a token and invitation from a member of the aegis) and a spirit that can cross the aegis (or is also invited into the aegis). Being in a situation where you are able to even cast this spell will be a great feat.