There is no way I am going to say everything about this Goddess; either for D&D or in general. So keeping that in mind, let's go.
Hecate, or sometimes, Hekate, is the Goddess of Witches, Ghosts and the Crossroads OR she is a Titan. OR she is something different.
Like some of the Olympian Gods, she is of the third or fourth generation. Her Great grandparents are namely Gaia (Earth) and Ouranos (Sky), same as Zeus' own grandparents. Their offspring was Crius, whom the D&DG gives as the Greater Titan of Gravity. Gaia (Earth) and Pontos (Sea) gave birth to Eurybia (Winds and Constellations; things that seemingly comes from the sea). Crius and Eurybia give birth to Perses (Titan of Destruction). He joins with the Titaness Asteria the Titan of stars and nighttime oracles. She herself was the daughter of Phoebe and Coeus, making her a half-sister to Leto the mother of Apollo and Artemis. Though there are other claims to her parentage. Some also claim she the daughter of Leto, which would make her Apollo and Artemis' half-sister.
Hecate then is the daughter of Peres and Asteria and of the same generation of Apollo, Artemis, Hermes, and Dionysus. While she is their generation she is often considered to be a Titan.
Like many of the Greek and later Roman Gods, Hecate has more than one, in what D&D came to call Portfolio. She is the Goddess of Nighttime as opposed to Nox the Personification of Night. She is the Goddess of Oracular power based on stars (as opposed to her semi-cousin Apollo who is the God of Oracles), one of the Goddess of the Moon. Her torches light the night. She is the goddess of the Crossroads. With her three faces, she can see the past, present, and future. And most notably, she is the Goddess of Witchcraft, Creatures of the Night and Ghosts.
Due to her rather complicated lineage, she also has dominion over Earth, Sky, and Sea.
As a Goddess, she is often seen in the company of large dogs from the Underworld, the Hellhounds and common house cats.
She is depicted in the D&DG as being Lawful Evil. I am not buying it. Lawful I can live with, but so much of what she does is both good and evil that Lawful Neutral is the much better choice.
Hecate is one of the few gods that retains her name in both the Greek and Roman versions. Though there is the Roman Goddess Trivia that also takes on some of what makes Hecate.
Goddess of Witchcraft
We know that many tablets and surviving scrolls have her mentioned in many curses and spells of protection against creatures of the night. According to Hesiod, "Hecate whom Zeus the son of Cronos honored above all. He gave her splendid gifts, to have a share of the earth and the unfruitful sea. She received honor also in starry heaven, and is honored exceedingly by the deathless gods."
Interestingly enough her domain over witchcraft relates to her being worshipped by Circe and Medea. Medea, in fact, is called a Priestess of Hecate. Medea is almost always described as a witch.
Hecate also appears in Shakespeare's Macbeth and mentioned in Hamlet. Each time due to her association with witches.
Lampad the Nymphae Avernales
The lampads are described as Underworld Nymphs. They were the constant companions to Hecate as a reward for Hecate taking part in the war against the Titans. Sometimes described as the Daughters of Nyx or of Daimones, they share a similar relationship to Hecate as the forest nymphs do with Artemis.
Lampads appear in the Pathfinder game, in Bestiary 4. Here is my interpretation.
Armor Class: 9 [10]
Hit Dice: 3d8 +16 (30)
Attacks: 0 (see below)
Damage: None
Special Attacks & Defenses: Cause feeblemindedness, malaise and death
Movement: 120’ (40’)
No. Appearing: 0 (1d4)
Save: Witch 3Morale: 8
Hoard Class: IX, XI x 10
Alignment: Neutral (Chaotic)
XP: 100
Nymphs are stunningly beautiful female fey creatures that closely resemble elven women. The lampad are nymphs of the underworld and desolate places. They appear similar to drow (dark elves), with grey ashen skin and long white hair. Anyone that sees a lampad must make a save vs. spells or become feebleminded as per the spell. If more than one lampad is present the victim is instantly killed on a failed save.
Lampads have the spell-casting abilities of a 6th level witch. They have their own language and speak common and the languages of the infernal realms.
Tears of the Lampad: These tears are extremely magical if a tear touches a mortal (not an elf though) they must make a save vs. poison at -4 or enter into a depression so deep they are unwilling to move or do anything. A victim will starve to death before they will attempt to bring themselves out of this malaise. Only a remove curse spell will allow them to return to their normal life.
The Empusa
I have used the Empusa many times in a lot of games. I have often categorized them as Lilim, or the Daughters of Lilith (who also shares a lot with Hecate) but in ancient myth they are the daughters, or at least the offspring, of Hecate.
Empusa (Lilim)
Armor Class: 3 [16]
Hit Dice: 8d8+4** (40 hp)
No. of Attacks: 2 claws and 1 bite or 1 weapon
Damage: 1d6 / 1d6 / 1d6 or 1d10
Special Attacks & Defenses: Magic resistance (25%), Lilim abilities, magical abilities, +1 magic weapons to hit, Intelligence drain
Movement: 120' (40')
Flying: 240’ (80’)
No. Appearing: 1d4
Save As: Witch 9
Morale: 8
Horde Class: X, XI
Alignment: Chaotic (evil)
XP: 2,380
These are believed to be the daughters of Lilith or Hecate and the various proto-demons. They are the most “demonic” of all of the Lilim. The Empusae (or “forcers-in”), like all Lilim, can appear as a stunningly beautiful woman or as a demon. The demonic form of the Empusa is one of the most hideous of all of the Lilim. The body remains mostly humanoid and female but covered in fine scales. Its legs become like those of a horse or ass and end in hooves that are made of brass or bronze. Its back supports a set of large leathery bat-like wings, similar to that of a succubus. It is its head that features its most horrible transformation. The creature’s long flowing tresses are replaced with a mass of snakes similar to that of a medusa. Its facial features are blocked by an area of complete darkness, only it’s glowing eyes are visible. It is said among sages that face of the Empusa is not shrouded in darkness, but it is so horrible that our minds block the vision from us. It is also said that other demons can actually see the Empusa’s face and run in fear from it. Its former delicate hands now end in razor-tipped claws. A long reptilian tail completes the picture.
An Empusa can appear as human, or it can also shapeshift into a large dire wolf (statistics as per Dire Wolf).
Unlike the combat avoidant Succubus, Empusae live for battle. They can either use their natural claw/claw/bite routine or use a flaming sword that strikes for 2d6 points of damage plus 1d6 of flame damage. Empusa gain to hit and damage bonuses due to their high strength as well.
The touch of an Empusa drains the Intelligence of the victim at 1 point per barehanded, not weaponed, attack.
The Greeks and the Egyptians had a long and complicated relationship. Greeks scholars used to say that everything they know came from the Egyptians. Back when I was doing the research for OMG: Egyptian Mythos I came across this saying all the time. This lead me to the Egyptian God of magic Heka. Like many before I noticed some similarities with Hecate and Heka. Both are their respective gods of magic. Both are heralded as "gifts" to the human race by their respective heads of their pantheon. Despite the similar portfolios and similarity in names there is no linguistic connection between the two.
