Full: Target foe is struck for 300 lightning damage and is knocked down. Dark Chain Lightning then hits each nearest foe in succession, knocking down each foe and striking for 10% less damage each time.
Concise: Deals 300 lightning damage and causes knock-down. Dark Chain Lightning then hits each nearest foe in succession, knocking-down each foe and doing 10% less damage each time.
Despite what the name suggests, this skill is not a spell. Thus counters specific to spells will not be able to counter this skill.
Dark Chain Lightning supposedly deals lightning damage, but skills like Mantra of Lightning do not reduce its damage.
Shelter and Protective Spirit are effective as they will negate a large portion of the damage and save healers in the group some time and energy.
Clumsiness is perfect to interrupt this attack, while the hex timing is important. However, it may not fully interrupt the attack, as Kuunavang is partially immune to them; however Signet of Clumsiness can be used in combination to almost ensure it is interrupted.