Conjure Ball Lightning

Version 0.30: This article may not be up to date for the latest stable release of Crawl.

Conjure Ball Lightning
Level	6
School1	Air
School2	Conjuration
Source(s)	Book of Chaos Book of the Spheres
Casting noise	6
Spell noise	25
Power Cap	200
Flags	Selfench

Creates a pack of ball lightnings, which seek out the nearest enemy before exploding in a huge blast of electricity. Casters are advised to use caution; the lightning is not mindful of what it may hit. The magic which keeps ball lightnings cohesive has limited range, so they may dissipate harmlessly if allowed to drift too far away from their caster before exploding.

Spell Details
Damage Formula	3 x 3d(5*power/24 - 2.5)
Max Damage	3 x 3d38 electricity
Max Power	200
Range	LOS
Targeting	Special
To-hit	Never misses
Special	Ignores 1/2 AC Creates 3 ball lightnings; explodes in 2-3 tile radius

Conjure Ball Lightning is a level 6 Air Magic/Conjurations spell which brings into existence 3 temporary instances of ball lightning.

Useful Info

Creates 3 ball lightning monsters - each one will individually home in on any existing, visible creature, exploding when in range. They will also explode if destroyed. If no hostile monsters are in sight, ball lightings generally disperse away from the player.

Each ball lightning deals 3d(5 * pow/24 - 2.5) electricity damage (min. 3d6), in a 2 or 3 tile radius (same chance). As BEAM_ELEC damage, the explosions ignore 1/2 of the target's AC.

Like Foxfire and player-created clouds, ball lightnings dissipate when out of the player's LOS. However, the explosions themselves can hit monsters outside LOS.

Strategy

Conjure Ball Lightning is an AOE spell that is strong in open areas. However, there's always the risk of the explosions hitting you.

Electricity resistance is highly recommended unless you want YASD. If you lack a reliable source of rElec (potions of resistance will work in a pinch, but not for general, repeated use), strongly consider choosing a different spell. Even with resistance, you can take upwards of 30 damage on a high roll.

If you decide to use CBL anyways, cast it only in where there is no other alternative and use these precautions: your target should be at the furthest possible range, with no nearby enemies (or plants); the enemy should ideally not be able to blink, summon, or use ranged attacks or spells (any of which might prematurely set off the ball lightnings); the player should move backwards right after casting, to get out of range; should the target be destroyed, the player should remain at a safe distance until all ball lightnings have detonated.

Tips & Tricks

• Ball lightning only has 1-2 HP, so you can intentionally detonate one with virtually any non-elemental attack. Stones and Magic Darts work well.
• Ball lightnings cannot see invisible. Casting the spell against an invisible enemy will simply cause your summons to wander aimlessly and ineffectively. If your target is, or has turned, invisible, you can always fire a projectile at a ball lightning to trigger detonation.
• Only very few, specific creatures have electricity resistance, making this a great all-around spell for area attacks on large numbers of creatures.

Monster Version

The monster version functions similarly to the player version, though monster-created ball lightnings do not dissipate when out of the monster's LOS.

The following enemies cast Conjure Ball Lightning:

• & Lom Lobon (3 x 3d25 damage)

The following enemies may be able to cast Conjure Ball Lightning, depending on their spell set:

• & Pandemonium lord (3.4% chance)

History

• Prior to 0.29, ball lightnings would home onto you if there were no valid targets.
• Prior to 0.26, the spell could conjure 2-5 instances of ball lightning, formula min(2 + pow / 100 + random2(pow / 50 + 1), 5), but damage was always 3d20. Also, random pandemonium lords couldn't cast this spell.
• In 0.25, ball lightning AI was changed to work like Foxfire. Previously, ball lightnings would home onto targets it didn't see, so it was easier to hit things from outside LOS. It could also home onto plants and other harmless "enemies".
• Prior to 0.14, CBL was a level 7 spell, and all ball lightnings were permanently confused.
• Prior to 0.10, ball lightnings had no duration after which they would explode.