I'm searching for an equivalent to the archmage prestige class ability from 3.5e, Arcane Fire (DMG, page 178), in previous editions (Player's Options, 2e, 1e or OD&D), but not 4e or 5e. Any official source is valid, including the magazines or campaign specific sources. It could be a kit ability, class ability or a racial ability too.
The Forgotten Realms has had, basically from its inception, the concept of “spellfire” (e.g. Spellfire, 1985). It also has “silver fire,” a related ability (e.g. The Seven Sisters, 1995).
Arcane fire, silver fire, and spellfire are all rare, high-level abilities that allow the manipulation of magic in its rawest form. They’re also known as “fire” but can do blasts of unresistable magic damage.
Spellfire is considerably more powerful and versatile, able to do many things other than blasts of raw magic, and those who wield it can power it from foes’ spells, rather than having to use their own power. Silver fire is massively more powerful, completely destroying any nonliving material in its large area and doing much more damage than arcane fire. Both silver fire and spellfire are heavily associated with the Realms goddess Mystra and her Weave, and basically rely upon her favor.
So arcane fire cannot be said to be either of these abilities. But it could be seen as a lesser, Mystra-optional approach to wielding raw magic in similar ways. Whether such a lesser option was available in earlier editions, however, I do not know—but I have done some searching on the web, and I can’t find any reference to any.