Host

A Host is a hostile mob that spawns on the Creep Day Event.

Spawning
Hosts will spawn in the Overworld during the Creep Day Event. They will despawn if the player gets too far away from them, or if the difficulty is set to Peaceful.

Hosts can be spawned using /summon nevermine.Host.

Drops
Hosts have a 100% chance to drop one Creeponia Realmstone and 32 Gunpowder at death. Neither drop can be increased with the Looting enchantment.

They will also drop 3 XP orbs when killed.

Behavior
Hosts don't directly attack the player. Every few seconds, Hosts will spawn several creepers underneath it. They may occasionally launch themselves into the air, damaging themselves as they come back down.

References/Sources
http://adventofascension.gamepedia.com/Host