The Ancient Herald is a boss monster that spawns during the Aporkalypse. If killed, it will respawn indefinitely, until the Aporkalypse ends.
The Ancient Herald will coalesce from the ground somewhere on the player's screen a short time after the Aporkalypse begins.
It attacks by diving into the ground, emitting a shockwave that destroys structures and sets them on fire, similar to the Iron Hulk Head or Leg, but with a larger radius. In addition, it will periodically cast an incantation, summoning various creatures and attacks to help it. It can summon either 4-5 Pig Ghosts, 4 Nightmare Creatures(no cap), 2 Meteors, or a lot of Poison Dart Frogs.