Terrors are summoned as though they are Monsters, and require a Controlled Gate to be able to enter play. They are equal to Monsters in their ability to Capture Cultists. That is, Monsters can protect Cultists against Terrors (and vice versa), and Great Old Ones can still Capture Cultists protected by Terrors. However, as Terrors are a different type of Unit, they are not vulnerable to abilities that specifically target Monsters.
To acquire a Terror, pay 2 Power and 2 Doom when it is your turn to perform a Ritual of Annihilation. You may still perform the Ritual, if you wish. Take your choice of available Terror Loyalty Cards and follow the instructions for placing your new figure on the Map.
Players may only purchase a single Loyalty Card in any given Doom Phase, so they may not gain a Neutral Monster in the same Doom Phase in which they acquire a Terror (and vice versa).
Once a Terror Loyalty Card has been acquired, it belongs to that player for the rest of the game. Only that player may Summon and control that Terror.