Portals are big, rocky gateways found in the forest, and are the main spawn-points of your enemies. Portals are usually closed during the day, but open at night to let out enemies, and will also open if they are attacked. When they are closed, portals can be safely passed by, but when open, they will spawn greed to attack anything that goes near it. They can be permanently destroyed by ordering knights/squires to attack them, but they will put up a fight. Once destroyed, the sky will turn blood red, and cries of anger will be heard. All your subjects will begin to retreat as if it were night time, and a blood moon will start mere seconds after the portal is destroyed. These blood moons caused by the destruction of a portal typically spawn a wave of enemies that is larger than that spawned during a natural blood moon. After destroying the last portal on one side of the island, the cliff/dock portal will become active.
Dock portals spawn on the dock of a new island, and must be defeated in order to build that island’s lighthouse. Dock portals will start closed, and will open once all other portals in that direction have been destroyed. Dock portals may not look intimidating, and pose about as much of a threat as any other portal, but they have about as much health as a cliff portal. Upon its defeat, the next night will become a blood moon, as it would with any other portal, and that side of the island will officially be safe (unless your defenses in the opposite direction fall).