Professor Flambardie's Grim Amulet

What's it called? Professor Flambardie's Grim Amulet (in brief, PFGA)

What does it do? After a good cast, this spell creates a 'twisted black amulet', which besides being a nice-looking piece of jewellery for daemonologists, is a requisite component for (and grants some protection from) the two main daemonic spells: Kelleflump's Irritating Demon and Doctor Kelleflump's Deadly Demon. In both cases, the amulet (which has already been described here) lasts a certain number of uses (probably skill-dependant, and usually not more than 12 or so casts even with good bonuses) before melting away.
The spell is a must if you intend to go around throwing evil imps at people. Because of its huge size and gp expenditure, along with relatively scarce components, the best way is to have a scroll of it and gathered components in a vault, and from time to time, re-stock your collection.

Where is it? As with all the hellish-dealing spells, it lurks inside the My Firste Demon-Summoning Booke! By Beatrix Faust grimoire, at the Unseen University Library.

What does it require? Lots of things: the focus of an octogram, a wand (not consumed), a small green crystal and a silver medallion (the last two consumed in the process).

What skills do I need? Amulet, Water, Wand, Summoning, Binding

Has it worked? The proper output should read something like this:

You prepare to cast Professor Flambardie's Grim Amulet.
You weigh the silver medallion in your hand, taking the measure of its form and material, and polish the surface clean and bright with a thought.
You take the Rhokshial's crystal firmly between thumb and forefinger, anointing the tip of your wand with the pure elemental essence of vitriol.
You sketch a series of eldritch runes onto the silver in dark, smoking lines of vitriol. As you draw, the runes writhe and twist, forming disturbing messages of madness and woe.
You whisper the three hidden names of the darkness, and the seven dread titles of the Lords who lurk in the rugose night beyond the edges of the world we know. One word more forces itself from your throat, the harsh-edged consonants scraping painfully across your palate, and echoes against unseen walls.
There is a sudden gust of chill, dank wind, carrying the moist unpleasant odour of old dead peat bogs and rotting garlic. You gather it firmly in your hands and twine it around the amulet, which twists and writhes, thrusting out spikes and hooks to catch and hold the demon-haunted air fast.
Your newly formed twisted black amulet glows with sullen power.

Help Information:

Professor Flambardie's Grim Amulet - Creates a protective amulet

Professor Flambardie wrote this spell to make sure that wizards would no longer be summoning demons without adequate equipment. Do be careful.

Magical items - Twisted Black Amulets

Recent advances in demonology have provided us, as you well know, with a whole set of new spells. One of these is Professor Flambardie's Grim Amulet, which creates a magical amulet that protects from some of the worst aspects of devil-dabbling-in, and which is of obligatory use for two of the evil imp spells: Kelleflump's Irritating Demon and Doctor Kelleflump's Deadly Demon.

The amulet is a curious work of art, certainly worth noting:

This piece of black-stained silver isn't quite flat, and isn't evenly rounded, as though it had been warped by a fire. The spikes and hooks around the rim have a disturbingly organic look, and the eldritch runes spiralling around the face are never the same twice. Occasionally, you can make out glimmers of meaning in the runes, but the bitter, doleful words always retreat and change before your mind can do more than take a glimpse of the vast, empty infinity of unpleasant truth behind the blackened silver.
Unpleasant-looking spikes and hooks of octarine light thrust at odd angles from its surface.
It is in excellent condition.

While being used the amulet doesn't seem to accumulate any visible damage. It will, though, from time to time, cause a small amount of damage to its user ("Your twisted black amulet emits a sullen black gloom and the surface shines with frost"). And after some more time and use, it will melt away. Many hypotheses have been suggested about how and why this happens: some think alignment might have something to do with it, that the number of thaums present when the spell to create it was cast could be decisive, or that the success in the skills when casting the spell is what really cuts the cake... Nothing is known for sure. It does seem to behave like an item with a fixed number of charges, variable in each amulet (like the pickling stick, so maybe also influenced by casting skills), but it doesn't respond to investigations with Fabrication Classification Identification ("The weave abruptly writhes, throwing out nasty-looking spikes and hooks. A black stain spreads over its surface before it shifts... sideways... and disappears somewhere to the left of down.").

Some research lies, therefore ahead. Meanwhile, we'll continue with the cumbersome crafting of these strange artefacts, that show an annoying tendency to unharness all bounds and set free ugly oozing demons into the Discworld...