The Crimson Portal is counted as a boss mob and appears within The Outer Lands from a boss room. The portal has 500 half-hearts of health.
The Crimson Portal will spawn, then for ten seconds will be invulnerable as it shoots out lightning which does no damage, but will spawn crimson banners about five to four blocks in all horizontal directions, (left, right, forward and backwards) and it will also spawn loot crates. Soon after this finishes, it will begin to summon Crimson Cultists in large waves. At once, it will only spawn 5 to 8 clerics or knights but will only spawn one unit type per wave. Very rarely, it will spawn a crimson praetor. Usually, a Crimson Portal will spawn one praetor in its lifetime.
The portal takes the appearance of a swirling red vortex, three blocks high and two blocks wide. It has an extremely dark black centre surrounded by a smaller aura of purple. In effect, it looks like an Eldritch Portal except stretched vertically and recolored. Unfortunately, no mobs as of yet can pass through the portal and walking at it will make you walk through and nothing more.
The portal has a spawn egg in the creative menu.
After it goes under half health it will begin to flicker. The less health it has, the more it flickers. When hit, it will wobble and its dimensions will warp, sometimes getting bigger and smaller. When it is killed, it will violently explode. When spawned, the lightning it uses to summon mobs stems from itself and is very thin and colored red. The lightning will make a very sharp noise and the portal itself has an ambient noise that sounds like distorted versions of the sound effects of Eldritch Guardians, Crimson Cultists, the Eldritch Portal and Eldritch Crabs.
It is impossible to farm a portal because it will close itself eventually, as every time it spawns a minion it will take a small amount of damage. The somewhat dire exception to this is if the portal itself spawns with the Undying bonus.
Wave System: Edit
Wave 1: 4 crimson banners 4 blocks in each horizontal direction.
Wave 2: until 8-12. Loot crates.
Afterwards, these are the possible waves:
1x Crimson Praetor.
4x Crimson Cleric.
4x - 6x Crimson knight.