Here are the list of Halloween Events that run from 10/1 to 11/2.
The dungeon gates, Killer Pumpkin and Halloween vendor are in Halloween Town. A GM will spawn a gate in Mainstreet that will take you to this area. There are 2 Dungeon gates. A very large higher level dungeon with multiple bosses and higher difficulty. A smaller easier dungeon with 1 boss and a mini boss. The dungeons only allow 1 pet with 1 pet slot. This is to prevent players from farming the entire dungeon with a mass pet zerg and not leaving anything for other players.