Sacrificial Magic is one of the two Dark Ones, (immoral forms of witchcraft) that solely relies on either the killing or sacrifice of one or more beings. The purpose of sacrificial magic is usually to kill and being, imprison a person, or reverse an imprisonment, such as a triquetra, which binds a person under the area where the triquetra is done. During this magic, tools like candles and fire are needed. The being(s) sacrified must be of relation to purpose.
Sacrificial Magic can also be used a domino effect to destroy a species; the sacrifice or killing of one being used to destroy the remaining beings. This, however takes formiddable power.
Both doing and reverting Sacrificial Magic takes a strong being, especially if it was originally done by somehow as powerful.
Triquetras are commonly used alongisde sacrificial spells.
Sacrificial Magic is one of the ways witchcraft has become corrupt since the past. It wasn't one of the Four Forms of Craft until the mid-1300s when witches began to kill and sacrifice innocent beings to imprison their enemies. This continued on and on until they began to use this magic to go as far as kill their enemies. It was then named one of the two most evil forms of the craft, the other being Essence Magic.
Sacrificial Magic was first introduced in the second book of the series.
Drake DeLuca used a triquetra to trap Nina Giordano under her father's chuch in Meadow Wood, as punishment to her love and his son, Alec. Drake killed a human, a Surgo Witch, and pure witch to use as sacrifice since Nina is a Hybrid.