The Seal of Strife's specific effect on siege equipment.
When the Lords of Dawn own the Seal of Strife in Interlude, the Revolutionaries of Dusk cannot use Siege Golems, Wild Hog Cannons or Swoop Cannons. If Dusk owns the seal, or there is no owner, siege weapons can be used.
The restriction is conditional on Dawn owning Strife and applies to Dusk’s siege-weapon use. It is not a general statement that all siege summons disappear whenever Seven Signs is active. Before preparing crystals and other summon supplies, check which side owns the seal and which cabal the intended siege participants belong to.
When the seal permits siege weapons, the particular summon still has its own class, item and battlefield conditions. Treat seal ownership as one check in the preparation, not as a replacement for the requirements of the chosen siege skill.