Wikia

Chain Lightning
Chain Lightning 30 yd range 3 sec cooldown 30.5% of base mana 2 sec cast Hurls a lightning bolt at the enemy, dealing X Nature damage and then jumping to additional nearby enemies. Affects 3 total targets.
Usable by
Class	Shaman
Properties
Type	Offensive
School	Nature
Cooldown	3 sec (GCD 1.5 sec)
Level required	28
TCG image

“

The air crackled with electricity as the bolt leapt from body to body, leaving the scent of charred flesh in its wake.

”

Chain Lightning is a core shaman ability learned at level 28. It deals direct damage to up to three targets.

Modified by Edit

2020

Glyph of Chain Lightning
Item Level 25Disenchants into:
Not disenchantable
Major Glyph
Classes: Shaman
Requires Level 25
Use: Permanently teaches you this glyph.
Your Chain Lightning spell now strikes 2 additional targets, but deals 10% less initial damage.
Sell Price: 1

All three hits are calculated individually. As such, it is possible (and fairly common) that only one or two hits critically hit.

Chain Lightning has a fairly high chance of triggering [Elemental Focus] (elemental spec) due to hitting multiple targets.

Be careful when using this spell if more mobs are nearby that aren't meant to be aggroed. While Chain Lightning may be more tempting to use for its lower cast time and higher damage output, it can easily cause adds.

Patch 5.2.0 (5-Mar-2013): Chain Lightning will now deal the same damage to subsequent targets as it does to the first.
Patch 2.3.0 (13-Nov-2007): Cast time was reduced to 2.0 (from 2.5), mana costs reduced, benefit from spell damage reduced appropriately.
Patch 1.6.0 (12-Jul-2005): Chain spells cast on PvP targets by an unflagged Shaman will now properly bounce to other PvP targets.