The Dreamlands Surface Monster expansion consists of 2 Shantaks, 3 Gnorri, and 4 Moonbeasts.
These Neutral Monsters can be used with ANY map expansion, they are not exclusive to the Dreamlands Map Expansion. By paying doom points in the doom phase, a player faction can permenantly gain control of a Neutral Monster and summon them alongside their other units. Neutral Monsters add new strategic options to factions, allowing players to overcome any weaknesses or disadvantages their particular faction may have.
Each monster has a special ability inherent to it, which is described on its loyalty card. Shantaks have the highly useful ability of carrying a Cultist with them when they move, so you can move two units for just 1 Power (as long as one is a Cultist, and the other a Shantak). Gnorri, Lovecraft's little-described amphibious horrors, give you a new boost towards victory. The Moonbeasts have a particularly obnoxious special power which makes them the bane of the other players.