Shock Pulse (known as Charged Bolt prior to July 2011) is a Primary Wizard skill unlocked at Level 3, launching electric charges that travel randomly on the floor, dealing lightning damage.
The charges emitted by this skill snake around erratically as they move forwards, making it hard to aim at any particular enemy. The best tactic is to cast it repeatedly as enemies advance towards the Wizard, thus guaranteeing that they will encounter multiple bolts.
The size of the monster hit box is important as well, since the bolts are cast far enough apart that most monsters will not be hit by two of them when they are melee range. Larger monsters though, are sure to take two or even three bolts, each of which deals the full damage. This is thus a fairly effective killing skill against large enemies.
The true essence of Electromagnetism exists on the threshold of the Ethereal and the Physical Realms. While it is very efficient to transform Mana into electrical energy, it is extremely difficult to control. This spell calls into being multiple pockets of lightning which seem to have a will of their own.
The Wizard has not only the fancy illegal spells at her disposal. Shock Pulse, something even the newest of Vizjerei neophytes learn, is one of the few spells she picked up in actual classes at the old mage clan, or possibly at Zann Esu before they kicked her out.
Skill Rune Effects
Refer to the Shock Pulse rune effects article for thorough descriptions of all five rune effects in this skill, including screenshots, videos, strategy tips, and other related information.
The Wizard and her carpet.
The spell familiar from Diablo I and Diablo II returns in Diablo III. As Charged Bolt did previously, Shock Pulse sends out a smattering of randomly-scattering charges, each of which deal minor damage to any enemy that passes over them. The strength of Shock Pulse comes not from the damage of each bolt, but from the carpeting effect of repeated casts, since it's a spell with no resource cost.
The following Wizard passives provide a benefit to Shock Pulse, runed or not:
Shock Pulse was first shown at BlizzCon 2008 (as Charged Bolt) when the Wizard debuted, where it was at Tier I on the Storm Skill Tree. Flux was able to try it out:
Three little crackling bits of lightning are sent forth along the ground, where they zig and zag a bit, but move in a more or less straight line away from the Sorceress. I didn’t use this spell much, but it seemed to me that the bolts spread out quite a bit more than they did in D2, and that made it hard to hit anything in front of me with more than one bolt. That’s now how it looks in screenshots though, where the bolts seem to carpet the dungeon floor quite nicely. More testing will be required.
It was still in the game at BlizzCon 2009; there, it had a much lower mana cost, and significantly lower damage than in 2008, indicating the spell was intended to be used more for the "carpet effect" of previous games. At BlizzCon 2010, it was still in the game but wasn't one of the Wizard's starting skills.
Skill tiers were removed for the July 2011 Press Event, allowing skills to unlock steadily from levels 1 to 30. Consequently, all skill levels were adjusted and Charged Bolt became a level 3 skill and was also renamed Shock Pulse.
The Diablo III Beta started in September 2011, and while it ran, all of the skills continued to undergo extensive iteration. Skill changes varied from changing the levels the skills are unlocked, to changes in resource cost, damage, and even function. A few skills were removed altogether, and a few new ones were added. Also, the entire skill system received an overhaul with the Beta Patch 13 update in February 2012, with physical runes replaced by rune effects that automatically unlock at various levels for the different skills.
Shock Pulse became a level 5 skill for the beta. Despite it being inefficient to use in most circumstances, Flux found one really good use for it:
Shock Pulse is the Wizard’s fastest boss-killing skill in the beta, despite the fact that you can not hit a single target with more than two of the bolts, and only that many by standing at point blank range. (Because the targets aren’t large enough. Presumably you’ll be able to bowl all 3 into a Siegebreaker-sized enemy every time.) This isn’t due to some massive damage of Shock Pulse, just the lack of other unruned skills that hit multiple times per use.
With the Beta Patch 8 of December 2011, all signature spells became free to cast at any level. With the Patch 13 changes, Shock Pulse was classified as a Primary skill and moved back to level 3.
See the Wizard skill archive for more details on previous versions of Shock Pulse (or Charged Bolt) and other Wizard skills.
Or see Charged Bolt (BlizzCon 2008) for the original version of this skill.
In Other Games
Charged Bolt was introduced in Diablo I, where it was, as it is now, a very cheap spell to cast multiple times in hopes of killing many enemies with a carpet of lightning. The spell calls in pockets of lightning that just crawls around randomly, in a general direction.
The second iteration of Charged Bolt was a Sorceress spell in Diablo II, and is basically identical in design. It's one of few Tier 1 spells in the skill trees that scale well even at higher levels, being quite useful at max level.
Shock Pulse can be seen in action on video here:
You can find pictures in the Diablo III screenshot and picture gallery: