Thunder Storm

Spell effects
Thunder Storm is a weather modifying Magick that effectively combines the Rain and Thunder Bolt Magicks together into a much more lethal form and can only be cast outdoors. When cast indoors, it has no effect other than to waste the 2 seconds of casting time. When cast outdoors, it causes the scene to darken considerably to 1/3 of its usual brightness and the entire scene will start to rain for 17.5 seconds. The rain will cause all units in the scene to become wet every 0.25 seconds.

After the rain has started for 2 seconds, bolts of lightning will start to shoot down from the sky to strike random locations in a radius of 20 around the casting wizard for the remainder of the 15.5 seconds. The bolts of lightning come in waves of 1 to 2 simultaneous bolts and the time between each wave is between 0.5 and 1.0 seconds, thus there can be as little as 15 waves of bolts or as many as 31 with an average of 21.1667 (15.5/0.75+0.5). This means that an average of 31.75 bolts will strike for any given Thunder Storm.

The location of each individual bolt of lightning is first selected to be a random location within 20 yards of the caster, biased towards locations that are further away (distance = 20 * sqrt(random), angle = 2 * PI * random). The game then finds the closest firm ground to this location. The bolt of lightning will then strike the most elevated target within a radius of 5 of this firm ground location. Water surfaces do not count as firm ground even if frozen (except the lake which is frozen by default in Chapter Five).

The bolts of lightning do not discriminate and is capable of striking enemies, allies as well as the casting wizard. Each bolt of lightning deals 5000 damage to unarmored units and deals 7500 damage to armored (wearing metal) units. If the target is wet, damage is doubled to 10000 and 15000 damage respectively. Frozen targets do not receive any additional damage.

Thunder Storm can be stopped by casting Nullify.

Achievements
The following achievement requires the use of Thunder Storm:

Pros

 * Kills quite a number of enemies if you can avoid dying to the Thunder Storm yourself.
 * Wets every unit on the scene which can kill enemy wizards if they attempt to use lightning elements without drying themselves.
 * Bolts targeted at wizards wearing the Cyber Robe will instantly heal them to full health due to the robe's lightning absorption trait.
 * Can be combined with Blizzard to freeze every wet unit or, when you want to be dry AND not chilled, with cold spells ( is very good).
 * The enemy can only have a water OR lightning immunity aura at the same time.
 * Looks very dangerous.

Cons

 * You also can only have water OR lightning immunity aura at the same time! Unless you will keep close to fellow wizards with the second immunity.
 * Can still be partially or completely be countered with Nullify, a lightning immunity aura (+Self), water immunity aura ((+Self)), self-shields (+Self) or shield bubbles (+Area).
 * Can kill allies, minions and the caster.
 * Can only be used outdoors.
 * Targeted locations are random. Bolts do not hit the most elevated targets like Thunder Bolt Magick does. Due to this lack of accuracy, sometimes simple thunderbolting does more damage.
 * The darkened scene can be difficult to see when Thunder Storm is active.
 * Rain can wet the caster as well as allies, preventing the use of crucial Magicks such as Revive.

Trivia

 * The elemental combination of Thunder Storm is also the strongest beam spell in the game. Likewise, its area cast version is the strongest AoE spell in the game. However, +Area is often preferred because trading the steam and lightning elements for arcane increases the radius significantly in exchange for slightly less damage.
 * Before patch v1.3.3.7, Thunder Storm used to be far more deadly to the casting wizard because the distance formula was "distance = 20 * random". This resulted in bolts of lightning having a chance of 25% of hitting the caster as compared to the current chance of 6.25% chance per bolt.
 * There are 6 ways to cast Thunder Storm: QFQFASA, FQFQASA, FFQQASA, QQFFASA, FQQFASA, QFFQASA.