Kingdom: Classic – Cliffs do not have the appearance of a portal (no swirling purple goo), but they do spawn greed for the final counterattack wave. Cliff portals cannot be destroyed.
It takes more damage to destroy than a small portal, and it is a longer run for the soldiers than any other portal and—the biggest difference—it reconstructs itself in three days if destroyed.
One potential danger is how far away the portal is from the Kingdom; depending on the island, the sun might be setting by the time the Kingdom's army arrives, at which time the Greed will already be launching their nightly raid. (The force behind their nightly raids is far less survivable than their portal defenses.) One way to avoid this problem is by ordering the assault the morning after a Blood Moon sets; the Greed do not to attack the night after a Blood Moon raid.
Except in the Skull Island (New Lands), when the portal is destroyed, the sky darkens but the Greed can mount no counter-assault, and so the Kingdom is safe for three nights. Periodically throughout those three nights, the portal's bricks lift into the air, marked with the Greed's purple magic, and smash back into place in the cliffs. Once the last block is replaced, the portal cracks back to life with the swirling purple goo, and the Greed resume their nightly raids on the Kingdom.
If a Blood Moon should occur on any of the three nights when the portal is incapacitated, the evil music plays, but the moon appears normal and no Greed attack the Kingdom.
Kingdom Two Crowns – Destroying the cliff portal may facilitate the access to the cave (as the Kingdom squad couldn't be suprised by a nightly wave on their way to the cliff), but it is not a requirement. Building walls closer to the cliff before lauching the assault or attacking right after a Blood Moon are good alternative methods. Destroying the cave secures that island and stops the greed spawning on it, even if there are still small portals on the sea side.
|Dec 11, 2018||All||1.0.0||Cliff portals give access to the cave.|
|Aug 9, 2016||All||1.0.0||Cliff portals can be destroyed, as they were in Classic before the final patch, but rebuild themselves after three days.|
|Apr 11, 2016||PC||1.2.0||Make hidden outer portals (cliff portals) invulnerable.|
|Oct 21, 2015||PC||1.0.0||Introduced.|
|Small portal Cliff portal Dock portal|