[scryfall]Lightning Bolt[/scryfall] is very powerful. Indeed, it’s too powerful to put in most formats. Being able to deal with quite a few threats with only one mana is extremely efficient and makes many creatures basically unplayable, which in turn makes designing sets more difficult, as any creature meant to be constructed playable than needs to dodge the Bolt or be very cheap.
So, the question is: Why not “Magical History of Lightning Bolt”? For the above reason. It’s not as interesting from a design point of view. Also, if that’s the way I’d go, how would I even delimit that? If I’d say “burn spells with casting cost of R”, than it would soon devolve into [scryfall]Shock[/scryfall]s anyhow. Maybe I’ll do “burn spells that deal 3” some day, but since Bolt is the progenitor of basically all but the X-spells that burn, I’d much rather use [scryfall]Shock[/scryfall] as the starting point.
The definition for these cards that I’m going to use is “Spells (instants, sorceries, enchantments) with casting cost of R, with no other mana cost, that deal 2 damage to a target”. This does leave out things like [scryfall]Kindle[/scryfall] and [scryfall]Magma Jet[/scryfall] that would definitely qualify under less strict rule, but I do want to keep this at a manageable length.
Before Shock
[scryfall]Earthbind[/scryfall] was in Alpha. Didn’t see much play due to how inferior it is to other removal in the set. This card is mostly infamous for the art. It survived until Revised and was removed after that. It was basically replaced by [scryfall]Vertigo[/scryfall] in Sixth Edition (1999), which was originally from Ice Age (1995). Didn’t survive long and hasn’t been seen since.
[scryfall]Burning Cloak[/scryfall] seems kind of complicated for Portal (1997), but this was a common theme in early red and still pops up every once in a while, but now more commonly in black.
Shock
After trying the waters with various cards that dealt three damage to a target, but cost more than Bolt, they just decided to go for it and downgrade it into [scryfall]Shock[/scryfall] in Stronghold in 1998. So, it took nine years for them to come around to it and accept that this was the way to go.
Since than it has become one of those true staples we see all the time. Perhaps not quite on par with [scryfall]Negate[/scryfall] and [scryfall]Dispel[/scryfall], or [scryfall]Giant Spider[/scryfall], but around [scryfall]Duress[/scryfall] definitely. It is just so simple, clean and effective, even though it’s effectiveness does rely quite a bit on the environment.
It was reprinted in many Core Sets since then: Sixth, Seventh, Eight, Ninth, Tenth, Magic 2012, Magic 2014 and now Magic 2019. It was also part of standard legal sets Onslaught and Aether Revolt, as well as an early FNM promo, World Championship Decks, Beatdown Box, Battlebond and one Duel Deck (Speed vs. Cunning).
There are a lot of variants on it, some few are strictly better, while most are different enough to see play on levels, where it’s not always obvious which one you would use. Generally they are quite beautifully designed.
Before Modern
[scryfall]Seal of Fire[/scryfall] (Nemesis, 2000) was a clear downgrade from Bolt, but it does dodge discard and you can also try to avoid counterspells by using it. I’m not familiar with Nemesis as a format, so there might have been some other weird themes into which this would fit well. It was later reprinted in Dissension as well as the Chandra deck in Jace vs. Chandra.
[scryfall]Assault // Battery[/scryfall] (Invasion, 2000) was a variant that could be done, because of its one half of a split card, which enabled all sorts of downgrades. It was later reprinted in Time Spiral as a Timeshifted card and Planechase.
[scryfall]Firebolt[/scryfall] (Odyssey, 2001) is not necessarily even that much worse than Bolt. It has been reprinted twice as part of duel decks and also in Eternal Masters.
Modern
There are 12 variants here (and a few more from previous sections).
Four of them are stricly better ([scryfall]Galvanic Blast[/scryfall], [scryfall]Tarfire[/scryfall], [scryfall]Burst Lightning[/scryfall], [scryfall]Wild Slash[/scryfall]) for various reasons, but generally not by much. The rest are inferior in some way, but superior in others. This inferiority is done either through not being able to target players (or planeswalkers for that matter) or shifting the card into a sorcery. None of these are strictly worse than [scryfall]Shock[/scryfall], though. Actually, of all of these, [scryfall]Shock[/scryfall] and [scryfall]Fiery Impulse[/scryfall] are the only ones that are strictly worse than [scryfall]Lightning Bolt[/scryfall]. Some even see play alongside it.
[scryfall]Galvanic Blast[/scryfall] (Mirrodin, 2003) sees regular play in various Affinity decks (or more precisely, Robots) in Modern. It does have a very high upside, actually competing with the original bolt in it’s power. Due to it’s power and nature, it hasn’t seen many reprints since, except for one Duel Deck (Elves vs. Inventors).
[scryfall]Dead // Gone[/scryfall] (Planar Chaos, 2007) is pretty basic removal, except that the other half seems like a pretty clear color pie break (although it is an effect red has had in at least one other card, which was actually in the same set and as such shouldn’t be held as a proof of anything).
[scryfall]Tarfire[/scryfall] (Lorwyn, 2008) is an interesting case. It is one of those few cards that have seen play when [scryfall]Lightning Bolt[/scryfall] has been available. This is due to the Tribal type, which, for example, has been used to enable Delirium in early some [scryfall]Death’s Shadow[/scryfall] decks. That did not last long, though.
Shards of Alara (2008) brought [scryfall]Magma Spray[/scryfall], which lacks the ability to target players (or planeswalkers), but is still quite strong due to the added text of exiling the creature if it happens to die. The effect has since been reprinted in both Journey Into Nyx and Amonkhet. In both cases for very good balance reasons because of various creatures with recursion abilities.
[scryfall]Burst Lightning[/scryfall] (Zendikar, 2009) is one of those strictly better cards than [scryfall]Shock[/scryfall]. Without a kick, it is exactly the same card, while it still has the option of being kicked. Because of the potential of the kick, it sees some play in cubes. It was reprinted in Modern Masters 2015.
[scryfall]Forked Bolt[/scryfall] (Rise of the Eldrazi, 2010) is strong enough to see some Legacy play. It has only seen a Duel Deck reprint, but it has variants, that have been made inferior in some ways (although, usually instants, so they are not strictly better). Maybe [scryfall]Dual Shot[/scryfall] should have been in this article, as it does deal exaclty 2 damage. It was printed twice in a short period of time in Shadows Over Innistrad and Ixalan.
[scryfall]Pillar of Flame[/scryfall] (Avacyn Restored, 2012) has a touch of [scryfall]Magma Spray[/scryfall] in it, but has been downgraded to Sorcery and upgraded to be able to hit players (and planeswalkers) as well. It was reprinted in Iconic Masters and sometimes finds it’s way into cubes.
[scryfall]Mugging[/scryfall] (Gatecrash, 2013) is an interesting variant, that didn’t see much play. I, personally, played it in some of my sideboards, because it was an easy way to push damage through in certain situations, where there were lifelinkers in play. That one turn was often enough.
[scryfall]Wild Slash[/scryfall] (Fate Reforged, 2015) is again strictly better. It has the potential to prevent damage prevention, which was often important in formats, where Protection was still a relevant mechanic.
[scryfall]Fiery Impulse[/scryfall] (Magic Origins, 2015) became an ubiquitous removal spell, despite [scryfall]Wild Slash[/scryfall] (and later [scryfall]Galvanic Bombardment[/scryfall] existing in the format, so apparently it was seen as the strongest of these variants (although the other two did see some play a well).
[scryfall]Galvanic Bombardment[/scryfall] (Eldritch Moon, 2016) had a lot of initial interest, but didn’t see much play at any point. It is a play on a mechanic that’s very old. [scryfall]Kindle[/scryfall] was all the way back from Tempest.
Finally, we have [scryfall]Shivan Fire[/scryfall], which is [scryfall]Burst Lightning[/scryfall] without the ability to hit players. This at least makes it not strictly better than [scryfall]Shock[/scryfall], which I personally like (ie. making choices between cards that are very closely related, but there’s no point to playing all of them).
All-in-all
[scryfall]Shock[/scryfall] seems like a basic building block of the game. You can play with it, but it feels like red requires at least one such effect available to it in Standard. You don’t always play them when playing red, but quite often you want at least access to them from the sideboard. Indeed, they might be a reason to play red, if there are a lot of low to the ground, aggressive decks in the format.
That 2 points to the face is often not insignificant as well. It might not be the primary plan, but it might still inform which version you want to play. There is also still the ability to target Planeswalkers as well, which [scryfall]Shock[/scryfall] has been errata’d to be able to do.