What a peculiar and mystical item this is! I've have this candle from quite some time and I'm very found of it. It's effects are extremely potent and extremely Neptunian. A little goes a long way, thus it has lasted a very long time.
Firstly, it burns in a Neptunian fashion. A certain astrologer once said, referring to the element of fire, that "something is either on fire or it is not." This candle defies such a clear binary. It lights easily. It stays lit, but the flame is consistently small, blue and extremely dim bordering on invisible. Although it's effects are viscerally felt when lit, I find myself checking to see if the candle is out. The flame is always there, but it offers little to no light.
As far as it's effects, I use it primarily for divination. Tarot interpretations are effortless to the point that the cards themselves become peripheral to the message at hand. Communication with spirits and guides is so clear that it feels as if the are in the room with you. Slipping into meditative trance states is immediate and visionary work is lucid to the point that it borders on delusion.
The insights I have gained while using this candle have been extremely healing and clarifying. I highly recommend it.
Note: I have had experiences with malevolent spirits entering my space post use. So please refer to Kaitlyn's advice on dealing with side effects. A quick smudging or a simple banishment has always done the trick for me.