In ZEN you are initiated into the masculine current. ZEN is the second Aethyr with a strong sexual content. The first being POP which is the polar opposite of ZEN. Generally speaking a female will have a strong sexual encounter in ZEN but not in POP. The experiences themselves will, of course, be highly personal and no two are likely to be identical.
ZEN provides the second half of the polar current (masculine) needed to raise your consciousness beyond the confines of the human mind. POP of course contained the first. If your encounter in POP was not sexual in nature than you will most likely have some kind of sexual encounter here.
ZEN contains the Vault of Sacrifice and Crucifixion, which you must lie in to achieve the rank of Adeptus Major and the accompanying energy increase that comes with that title. The Guide here is a sexually attractive male embodying the masculine current (sometimes, but not always, seen as the god Horus) who will lead you to an imposing Vault (or the symbolic equivalent of it). Once here, some form of drama will unfold where you will be asked to sacrifice or crucify yourself. Quite often, you are unaware of your physical self while here, and you will be completely focused on the initiation. This singular focus is meant to simulate what you would do if this was an actual physical encounter.
The initiation in ZEN brings about the dissolution of personality, a necessary first step to experience your individuality. At the proper time, sacrifice need not be terrifying or unpleasant. No one forces you to sacrifice yourself for others. Your own desire will impel you to do so. The Vault of ZEN gives you a place to do so with safety and without having to let go of your present physical life. The drama ends when you take on enough of the masculine current to complete your leap in consciousness. At this point you take on a new magical rank (Adeptus Major) and a new consciousness.
* additional source material: "Enochian Magick" by Gerald J. Schueler, "The Golden Dawn" by Israel Regardie