When cast, the Lightning will cause three bolts of lightning to rain down from the sky, targeting the 3 troops/buildings with the highest hitpoints within its AoE (Area of Effect), dealing very high damage and a brief stun.
The Lightning spell can be used to finish off lowered Crown Towers or destroy low-medium hitpoints units that deployed behind a Tower to damage the Tower and the units.
This spell is extremely effective against Musketeers, Wizards, and Witches, especially next to enemy Crown Towers, as the spell targets the 3 troops/buildings with the highest amount of hitpoints in its radius. This can decimate most pushes.
As the Lightning strikes once on each target, it will strike fewer than three times if there are only one or two enemy troops/buildings within its radius, reducing its value.
When using the Lightning, it is important to be designate the targets of the spell in its radius. It is best to refrain from showing the opponent the Lightning until the opportunity for the highest Elixir advantage possible arises.
When trying to destroy the enemy Crown Tower at the last few seconds of the game, be careful, as any medium-high hitpoint units in its radius will be targeted instead by the Lightning, as in such situations the Crown Tower will have relatively low health, possibly even lower than a Skeleton. Instead, cast the Lightning towards the corner of the Tower while it is within its radius to avoid targeting other units.
The Elixir trade-off for using a Lightning is very high, giving the enemy an Elixir advantage in most cases. The Lightning Spell is also ineffective against high-hitpoint units such as the Giant or Prince.
A good alternative to the Lightning with a smaller area of effect yet yielding higher damage is the Rocket. Although it utilizes the same amount of Elixir, the Rocket does not discriminate between troops with higher and lower hitpoints and instead damages all troops/buildings in its radius.
The Lightning can be paired with a 3 Elixir card such as the Minions or Arrows to eliminate any lingering troop(s) weakened by the Lightning.
The Lightning is very effective against the Sparky as it will reset Sparky's damage while also dealing high damage to her and other supporting troops.
Barbarians can shield any medium HP units from Lightning, as their HP is higher. For example, Three Musketeers.
The Lightning card was added with Clash Royale's soft launch on 4/1/16.
On 19/9/16, a Balance Update gave the Lightning the ability to stun targets for 0.5 sec.
The Lightning's animation is similar to its counterpart in Clash of Clans.
It is tied with the Rocket for the most expensive spell at 6 Elixir, not counting the Mirror which does not have a determined Elixir cost.
If there are less than 3 targets in the Lightning's radius, then it will not fire all 3 bolts. It is possible to waste 6 elixir this way if there are no units in its radius.
In Clash Royale the Lightning can only hit three buildings or troops, whereas in Clash of Clans, it can hit any troops or buildings in its damage radius, although it also features lightning bolts.
The Zap is similar to the Lightning in its appearance and also has an equal-duration stun, but is very different in its attack and use.
Although the Lightning has a circular radius, it can only hit 3 targets in that radius, leaving other troops and buildings that were also in the spell radius untouched, a property unique to the Lightning.