Mourning Wood

Mourning Wood is a hardmode miniboss encountered during the mid-to-final waves of the Pumpkin Moon.

During combat, the Mourning Wood alternates between firing a volley of flaming spikes straight at the player that pass through blocks, and firing a jet of spark-like flames  that are affected by gravity and stay on the ground for a while, doing damage to players that touch them. This can be frustrating while fending off other enemies, but using a flight accessory helps immensely, as the flames aren't too accurate to the player's location.

Tips
Tips Video http://youtu.be/HzQDKlYa2s4
 * Floats through blocks to reach the target player, resembling Wraith's behavior, but otherwise walks on surfaces and cannot jump.
 * Due to this it's perfectly capable of fitting into spaces much less than its size.
 * They do not despawn after killing all available players. This, combined with their high damage potential and ability to phase through solid blocks, means that an unprepared player can easily spend most of the night being spawn-camped by one or more Mourning Woods. Making a bed in or above your intended arena, with space to start moving as soon as you respawn, is essential to avoid getting trapped and killed repeatedly.

Trivia

 * The name "Mourning Wood" appears to be a play on the term "Morning Wood"