The Summon Spectre is a conjuration effect from the Witchery mod. When performed, after about 30 seconds, a Spectre will be spawned. There is a small chance that a Poltergeist will also spawn. It can be performed by using a Wormwood, Wool of Bat, and Graveyard Dust on a Brazier, then lighting it with a Flint and Steel. The Brazier must have Altar power, which means it must be within 15 blocks of the Altar.