It is pretty much correct to expect this roughly along the lines of Dungeons & Dragons, or any such games you might know.
In the sense of the ritual involved and the outcomes (expected): one recites a spell, reads from or writes on [a scroll, shard, metal sheet, wax tablet etc.] and then observes the result (or lack thereof). This could be beneficial or detrimental. And with a 'modern' view attribution of cause and effect from these rituals we would of course view these to be either 'unconnected', 'merely psychological', perhaps even 'delusional'.
So: Not always and in every sense of Dungeons&Dragons. 'Whether or not' or 'if, then how' modern rationalists might think these spells 'worked' (since we are mostly modern: 'or not') is much less the focus of the following than a description of the practices and the evidence that remained in the form of literary finds, direct or indirect.
Not only in Ephesus but throughout the ancient world these practices were quite widespread.
We do not only have references to these scrolls, outside of Christian texts.
We do have some of these very scrolls:
The Greek versions of these magical scrolls, which somewhat resemble the Mesopotamian, Roman or Egyptian counterparts, are discussed under the collective name Papyri Graecae Magicae or Greek Magical Papyri.
The content of these magical scrolls is pretty much similar to defixiones or "curse tablets", and can range in the powers summoned from binding people, letting evil befall them and so on. But also love magic, spells of all kinds, making or breaking a harvest.
Actual "fire balls" would not feature that much in them, but calling a demon, evil spirit or the like to harm the butcher you don't like living on 3rd street in Pompeii in 78 AD would have been surely interpreted as "worked nicely" by the issuer of such a scroll.
That there may have been public events burning such scrolls is entirely possible. What is somewhat less likely is that this took place at such an early time during the spread of Christianity on such a scale.
That is: due to Christian influence.
It is assumed that most magical books/scrolls were indeed destroyed during Roman times. Representing a trend over in Roman attitudes and law from the prohibition of carmina mala as early as the XII tables over the late republican Sullan Lex Cornelia de sicariis et veneficiis, which could be analysed as:
[…] the concern of the original Lex Cornelia was with harmful and uncanny actions, and that this broadened out over time into a wider concern with religious deviance, even though the latter never entirely displaced the former.
— James B. Rives: "Magic in Roman Law: The Reconstruction of a Crime", Classical Antiquity, Vol. 22, No. 2, 2003, pp. 313-339. jstor
One such example of book burning only slightly before the events described in Acts is reported in Suetonius' Lives of the Twelve Caesars (Suet. Aug. 31.1), where Augustus is said to on becoming pontifex maximus he burned all such books within his reach, with very few exceptions.
Act 19,19 is often interpreted as exactly such an event, with Paul thus probably given some undue credit on this in the preceding lines of Acts.
Other non-Christian references to these scrolls, forbidden books, and their destruction, are for example in Ammianus Marcellinus, (Amm. Marc. XXVIII.i.26, XXIX.i.41).
The term 'sorcerer' is in this case perhaps a bit misleading. These did not have to be 'professionals', or specialists. This was an almost everyday activity, practiced by a lot of people. So the term primarily refers to 'people doing these things'. Those 'specialising' in these kinds of practices were called Magi or magoi. Also compare the different translations possible and used for the passage Act 19,19, like: "those who practiced magical arts", "who had practiced occult arts", "who had practiced the superfluous arts", "who had followed curious arts"…
Compare the Greek text of this passage where it says:
ἱκανοὶ δὲ τῶν τὰ περίεργα πραξάντων συνενέγκαντες τὰς βίβλους κατέκαιον ἐνώπιον πάντων, καὶ συνεψήφισαν τὰς τιμὰς αὐτῶν καὶ εὗρον ἀργυρίου μυριάδας πέντε.
With περίεργα: periergos:
Definition: of persons: over-careful; curious, meddling, a busy-body; of things: over-wrought; superfluous; curious, uncanny; subst: curious arts, magic.
Thus clearly encompassing 'all who tried this, possessed such books'.
To bind that back to the source material prompting this question: For a nice illustration of the principle applied to interpreting biblical texts — which contain much more allusions to these practices, also in the Hebrew world — read, but try not to read too much into it, Morton Smith: "Jesus the Magician".
Two examples for the content of such scrolls/books might be this:
*Tested spell for invisibility: A great work. Take an eye of an ape or of a corpse that has died a violent death and a plant of peony (he means the rose). Rub these with oil of lily, and as you are rubbing / them from the right to the left, say the spell as follows:
"I am ANUBIS, I am OSR-PHRE I am OSOT SORONOUIER , I am OSIRIS whom SETH destroyed. Rise up infernal daimon IO ERBETH IO PHOBETH IO PAKERBETH IO APOMPS , whatever I NN order you to do, be obedient to me.
And if you wish to become invisible, rub just your face with the concoction, and you will be invisible for as long as you wish. And if you wish to be visible again, move from west to east and say this name, and you will be obvious and visible to all / men.
The name is:
"MARMARIAOTH MARMARIPHEGGE, make me, NN, visible to all men on this day, immediately, immediately; quickly, quickly!"
This works very well.
Translated by: E.N. 0'Neil, Cf PGM I.222–31. […]
- A restraining [rite] for anything, works even on chariots.
It also causes enmity / and sickness, cuts down, destroys, and overturns, for [whatever] you wish. The spell [in it], when said, conjures daimons [out] and makes them enter [objects or people]. Engrave in a plate [made] of lead from a cold-water channel what you want to happen, and when you have consecrated it with bitter aromatics such as myrrh, bdellium, styrax, and aloes and thyme, / with river mud, late in the evening or in the middle of the night, where there is a stream or the drain of a bath, having tied a cord [to the plate] throw it into the stream-or into the sea-[and let it] be carried along. Use the cord so that, when you wish, you can undo [the spell]. Then should you wish to break [the spell], untie the plate. Say the formula 7 times and you will see something wonderful. Then go away without turning back / or giving an answer to anyone, and when you have washed and immersed yourself, go up to your own [room] and rest, and use [only] vegetable food. Write [the spell] with a headless bronze needle.
The text to be written is:
"I conjure you, lord Osiris, by your holy names OUCHIOCH OUSENARATH, Osiris, OUSERRANNOUPHTHI OSORNOUPHE
Osiris-Mnevis, OUSERSETEMENTH, AMARA MACHI CHOMASO EMMAI SERBONIEMER ISIS ARATOPHI ERACHAX ESEOIOTH ARBIOTHI AMEN CH[N]OUM(?) MON-MONT OUZATHI PER OKUNNEPHER EN OOO, I give over to you, lord Osiris, and I deposit with you this matter / " (add the usual).
But if you cause [the plate] to be buried or [slink in] river or land or sea or stream or coffin or in a well, write the Orphic formula, saying, "ASKEI KAI TASKEI" and, taking a black thread, make 365 knots 63 and bind [the thread] around the outside of the plate saying the same formula again and, "Keep him who is held (or "bound"), or whatever you do. And thus [the plate] / is deposited. For Selene, when she goes through the undeeworld, breaks whatever [spell] she finds. But when this [rite] has been performed, [the spell] remains [unbroken] so long as you say over [the formula] daily at this spot [where the plate is deposited]. Do not hastily share [this information] with anyone, for you will find [its like (?)only] with much labor.
Translation.: Morton Smith.
For context of these beliefs and practices in antiquity, or how to interpret them now:
The episode about the burning of the magical books in Ephesus in the Acts of the Apostles is well known and typical of many such instances. According to SuetoniusAugustus ordered 2,000 magical scrolls to be burned in the year 13 B.C. Indeed, the first centuries of the Christian era saw many burnings of books, often of magical books, and not a few burnings that included the magicians themselves.
As a result of these acts of suppression, the magicians and their literature went underground. The papyri themselves testify to this by the constantly recurring admonition to keep the books secret. Yet the systematic destruction of the magical literature over a long period of time resulted in the disappearance of most of the original texts by the end of antiquity. To us in the twentieth century, terms such as "underground literature" and "suppressed literature" are well known as descriptions of contemporary phenomena. We also know that such literature is extremely important for the understanding of what people are really thinking and doing in a particular time, geographical area, or cultural context.
Magical beliefs and practices can hardly be overestimated in their importance for the daily life of the people. The religious beliefs and practices of most people were identical with some form of magic, and the neat distinctions we make today between approved and disapproved forms of religion — calling the former "religion" and "church" and the latter "magic" and "cult" — did not exist in antiquity except among a few intellectuals.
— Hans Dieter Betz: "The Greek Magical Papyri in Translation. Including the Demotic Spells", University of Chicago Press: Chicago, London, 1986, p130.
To not overstretch the similarity between 'real' magic practices of antiquity and almost purely 'weaponised' Dungeons & Dragons fireball usage, we need to consider that while most of the original literature on this is lost, at least the surviving papyri in their majority do not focus on 'summoning fire' for destruction.
'Real fire' for the eyes of the 'believers'/'customers' to see was part of some of these ritual performances sometimes as well. Mainly in a manner we today would probably classify as a mix between 'occult practices' and 'stage magic/tricks', like described by 'Christian skeptic' Hippolytus as:
But (the sorcerer) produces a burning demon, by tracing on the wall whatever figure he wishes, and then covertly smearing it with a drug mixed according to this manner, viz., of Laconian and Zacynthian asphalt — while next, as if under the influence of prophetic frenzy, he moves the lamp towards the wall. The drug, however, is burned with considerable splendour. And that a fiery Hecate seems to career through air, he contrives in the mode following. Concealing a certain accomplice in a place which he wishes, (and) taking aside his dupes, he persuades them (to believe himself), alleging that he will exhibit a flaming demon riding through the air. Now he exhorts them immediately to keep their eyes fixed until they see the flame in the air, and that (then), veiling themselves, they should fall on their face until he himself should call them; and after having given them these instructions, he, on a moonless night, in verses speaks thus:—
Infernal, and earthy, and supernal Bombo, come!
Saint of streets, and brilliant one, that strays by night;
Foe of radiance, but friend and mate of gloom;
In howl of dogs rejoicing, and in crimson gore,
Wading 'mid corpses through tombs of lifeless dust,
Panting for blood; with fear convulsing men.
Gorgo, and Mormo, and Luna, and of many shapes,
Come, propitious, to our sacrificial rites!
Hippolytus Haer. 4.28–42, here: 4.35
If the papyri talk of 'fire', they most often do in order to invoke a burning sensation of lust and love in another being
The magical operation is called πραξις, πραγματεια, […]
In the description of the magical operation, the first matter to be considered is the relationship between the magician and the user. The magician is the person who possesses the knowledge of the proper instructions about the ritual action and the spell. The ritual action involves the performance of a ritual, and the ritual words entail the reciting, or writing, of the spells.
The spell most often is called […] (“binding” spell). The erotic spell most often is called […] (“erotic potion”), or […] (“eros-binding” spell), or even εμπυρον, erotic spell “by means of fire”).
Generally, they can be categorised as:
The Greek and Demotic magical papyri can be divided into broad categories such as prayers and invocations to the gods, spells for revelation and divination and oracles, spells and rites to acquire an assistant, spells for the personal daimon, theurgic spells, erotic spells, spells for favour and victory, spells and charms for memory and foreknowledge, medical spells, prescriptions, amulets and phylacteries, spells and phylacteries against daimons, horoscopes and astrology, spells for silencing and subjecting, or inflicting harm, and finally spells to release from spells. Clearly, the material is extremely rich and varied.
— Eleni Pachoumi: "The Concepts of the Divine in the Greek Magical Papyri", Mohr Siebeck: Tübingen, 2017.
As potentially ubiquitous magic practices were in antiquity, some viewed them with pragmatism, others with suspicion, contempt, fear or even legal oppression. As already seen, magical practices became generally less favoured in Roman late republican times and even more so in imperial times. But while the emperors went against magic in public, it was a few of them who were most closely connected to applied sorcery in the form of necromancy:
The Romans generally took a dimmer view of the practitioners of necromancy than the Greeks did. Already in the late Republic, one could abuse one's enemies by attributing necromantic practices to them, and the deviance of necromancy was built up by association with human sacrifice. In the imperial period, if not before, the practice of necromancy would have fallen foul of general laws against magic and divination and (in the cases of alleged human sacrifices) murder.
Under the empire, the practice was associated above all with the emperors themselves and with their supposed enemies, who allegedly used it to divine the occasions of their deaths. The attribution of necromancy to the emperors helped to portray them as distracted, desperate, and excessive in a number of ways. The emperors' fear of the performance of necromancy to divine the occasions of their deaths may have been caused not just by the fear of the implicit hostile intent and of its revolutionary resonances, but also by the fear that such an act of prediction might in itself hasten their demise.
Among Republican Romans, necromancy is explicitly associated with Vatinius, Nigidius Figulus, Appius Claudius Pulcher, and Sextus Pompey. Cicero accuses Vatinius of the practice in a superb piece of invective in 56 B.C.:
You, who arc accustomed to call yourself a Pythagorean and to conceal behind the name of a most learned nun your monstrous and barbarian customs, what crookedness of mind possessed you, what frenzy so great, that, although you have undertaken unheard of criminal rites, although you arc accustomed to call up the spirits of the dead, although you are accustomed to make sacrifices to the ghosts of the dead with the entrails of boys…
— Cicero Against Vatinius
[Necromancy] constituted a convenient way of expressing their [the emperors'] exceptional status, their distracted insanity, their anxiety about their own position, their attachment to bizarre un-Roman customs, their preparedness to abuse their wealth and power, their homicidal cruelty and ensuing guilt, and their desire to compete with the gods.
— Daniel Qgden: "Greek and Roman Necromancy", Princeton University Press: Princeton, Oxford, 2001.
Again, on the D&D fire balls, one might recall that 'any sufficiently advanced technology is indistinguishable from magic”. This is profoundly true when we analyse a certain Greek weapon, which was well known for its magical effects but quite unknown for its mechanism of action because of its arcane art in conjuring it up, as it is still a secret to us:
[…] it was only natural that the one Power took on the forms and names of many powers—gods, daemons, heroes, disembodied souls—who were willing, or even eager, to work for the magus. When the magus summoned these powers by means of his magical knowledge and technique, he could either help and heal or destroy and kill. […]
Many achievements of ancient technology border on the magical, especially if their secret was well kept. In fact, they could be described as Magia naturalis. A good example is Greek Fire, a highly combustible mixture useful in naval warfare because it burned on water. Something like it was already used in Hellenistic times, but its invention is usually attributed to Byzantine alchemists. To a Byzantine theologian with an interest in magic, Michael Psellos, we owe a fascinating description of the secret rituals performed by the empress Zoe (c. 978–1050) in her private laboratory inside the palace; here she experimented with various perfumes, aromata, which, as Psellos carefully puts it, she "offered to God" (Chronographia 6, chs. 64ff.). […]
To the original mixture of sulfur, tow, and chips of pinewood, the Byzantine wizards added quicklime and crude mineral oil, probably also resin and pitch. Specially trained technicians sprayed the liquid through a kind of flamethrower (a portable pump with a bronze tube attached to it) at the vessels of the enemy. The effects—both material and psychological—must have been devastating. The composition itself and its proper use in combat were kept secret.
— Georg Luck: "Arcana Mundi. Magic and the Occult in the Greek and Roman Worlds. A Collection of Ancient Texts", The Johns Hopkins University Press: Baltimore, 2006.