The 5th-century CE Neoplatonist Proclus is often made to stand for his age, as the foremost thinker of a period in which a novel kind of piety and ritual practice had come to the fore, whether that is characterized as irrational, Oriental, theurgical or something else. But in fact, insofar as his philosophy was “cutting edge”, he stands in great intellectual contrast to his non-philosopher contemporaries, who were often more strongly influenced by Stoic ideas that had permeated Greco-Roman culture for centuries. And insofar as he philosophizes about the beliefs and practices of a wider population, he does not stop at the recent past, but seeks to make sense of the entirety of pagan intellectual history from Homer and Hesiod to his own personal experiences.
As such, Proclus can often serve as a starting-point for surveying (what we call) ancient paganism as a whole, and of making sense of it, even if we keep in mind that his interpretations were not necessarily shared with those whose beliefs he is trying to make sense of. One instance of this is a brief passage in On the Hieratic Art according to the Greeks, where Proclus lists a few simple substances that can accomplish ritual operations without (as was usually the case) requiring interaction with other objects and actions. One category he employs is that of protection, phylakḗ; in other words, he is listing the simplest protective amulets or phylacteries (phylaktḗria). All of these can be parallelled in other sources (which are not “Oriental” or “theurgical”, but mainstream), and from these, we can see that the protection meant is primarily that against daemons and curses, as well as illnesses thought to be caused by daemons (like epilepsy).
The brief passage of Proclus must also be taken together with a critical discussion of pagan beliefs about daemons in the Byzantine polymath Michael Psellus, who is getting his information from the Neoplatonist’s compendium of Chaldaic doctrines (which, like any of his commentaries on Plato, was something far more comprehensive than a simple commentary on the Chaldaic Oracles).
Edit: after translating the passages from Proclus and Psellus, tracing parallels and writing this introduction, I found another very strong parallel in the Lycophron and (taken hence?) the Odyssey scholia (section 4 below). The similarities are so striking as to suggest some close connection, but there is enough of a difference that the scholium cannot simply be taken from Proclus or vice versa. The scholium includes some materials that are hard to find parallels for, has its own explanatory mechanism (antipathy), and also refers explicitly to the tripartite taxonomy of animals, plants and stones, which is only implicit in the Proclian passage.
2 Proclus, On the Hieratic Art p. 151
Sometimes, even one herb or one stone suffices for an operation (ergos). […] For protection: laurel (dáphnē, cf. Purification by Fire and Laurel), boxthorn/buckthorn (rhámnos,* cf. Poem On Herbs 2), squill (skílla, cf. Theophrastus, On Superstition 12), coral (kourálios, cf. Damigeron, On Stones 7), diamond (adámas, cf. Damigeron, On Stones 3) and jasper (íaspis, cf. Jasper as well as Iron Against Daemons).
* According to the veterinarian writer Vegetius, rhámnos (lat. ramnus or rhamnus) is also squill, like skílla (lat. scilla).
3 From Psellus, Philosophical Essay 19 (ed. Duffy)
Daemons cannot in the least be burned by fire; for one must not believe the Chaldaic ravings that there is a certain kind of daemons fearing the diamond stone (adámas), the coral (kourálios), the “man-slaying sword” (androphónos xíphos, cf. Iron Against Daemons),* and the thunderbolt (keraunós).† The Chaldaean diviners, when they wish to drive away (apotrep-) this kind (of daemon) in their unholy operations, lay these things onto their altars.
* “Man-slaying sword” is a poetic expression, and so may be quoted from the Chaldaic Oracles.
† From context, it seems probable (although not certain) that Psellus has misread keraúnios, a certain kind of stone, as keraunós, “thunderbolt”. The stone is also mentioned in Damigeron, On Stones 12 and On Stones and their Engravings. For further information and references, see Keraunios.
4 Scholia on Odyssey 10.305
(Hermes gave Odysseus the plant Moly) so that he would not be harmed by the spells (pharmaka) of (Circe). And moly, according to the physicians, is wild rue. But allegorically speaking, even if he does not mean moly, (still?,) laurel, fleabane (kónyza),* rhámnos, willow (itéa), star-fish (astḕr thalássios),† the stone jasper, and many other plants, animals and stones have an antipathy† against magical attacks (? magikoi paratropoi).
* According to Pseudo-Dioscorides, De herbis femininis 28, fleabane among other things helps against epilepsy and serpent venom; the latter is parallelled in other sources (Nicander). Oribasius notes a prophylactic use against snake bites (Eclogae medicamentorum 123).
† Antipathy is a natural (or, as we might say, supernatural) power of one kind of thing against some other thing. Thus, according to Pseudo-Democritus, On Sympathies and Antipathies 28, a star fish hanging under the roof of a house has an antipathetic effect against any attack of madness or raving (mania).