Introduction to Lightning-based spells
The power of Chain Lightning (CL) has baffled many players over the life span of the game of Diablo. This spell is a fairly high level spell, appearing on page 3 of the spellbook and for most players, they learn it from a book bought from Adria, well after they have learned the lesser Lightning based spells Charged Bolt (CB) and Lightning (Ltng). Learning Charged Bolt and Lightning is fairly straightforward, even at high spell levels (spell levels 14 - 20), but Chain Lightning gives more problems at these levels than it seems to solve. Thus Yours Truly (YT), a regular who's pretty adept at CL, wants to give a bit of help to those who want or need it.

The basics about CL
CL will sent a stream of Lightning into the direction of the mouse-pointer, where you right-clicked, as well as one stream to all the monsters within range. This range is determined by the caster's CL spell level. The higher the spell in your spellbook, the wider the range CL will search for monsters to send a stream to. The monsters can be hiding behind walls and other obstacles, even be Lightning resistant or immune, it doesn't matter, they still get targeted. The damage done by CL is in a range from 2 to 2 * clvl, thus not spell level dependent at all. This is similar to Lightning damage multiplied by 2. Damage done by both CL & Ltng streams is continuous. The Streams continue to travel and inflict damage until they hit a solid surface, unlike Charged Bolts (which lose their power when they hit any enemies). The CL spell level also determines the length of the streams. The longer the streams the higher their potential for damage (which is continuous, an often overlooked feature of Lightning-based streams). One caveat, CL uses a large number of the available spell-slots that the game internals use. When this happens, it is referred to as CL-gapping, a term I will use from time to time. Last note, the targeting range of CL has nothing to do with your Light Radius.

The 3 main CL power ranges
1. Slvl 1-4 Low levels, low damage
2. Slvl 7-11 Medium levels, useable damage
3. Slvl 14-20 High levels, outright destructive

The unlisted spell levels 5 and 6 can fall between low and medium. Sometimes CL behavior from these slvl casts are like low level CL, other times like medium. Same for the CL slvls of 12 and 13. The boundaries are often vague and any cast from CL is always dependent on the number of monsters it can reach at the time of casting. Low slvl here also means short streams of CL, so casting can be very rapid, depending on character class. Starting with CL casting before you are surrounded can allow continuous casting of CL without any problem, though in a future post Yours Truly hopes to demonstrate that Charged Bolt is really a better alternative to low slvl CL in these situation (please take my word for it right now). This may be a good time to introduce another caveat that Yours Truly has been investigating, how does the CL spell deal with moving monsters? The simple answer is that it doesn't. It leaves any moving monsters out of its range evaluations and doesn't send any streams out to them. This applies mainly to monsters which are halfway between game-tiles. Monsters which only just start to move at time of CL casting may be targeted, but may not be.
Note by KoP: See also “A Study of Charged Bolt” now on this site’s Tips page.

Low CL spell levels
At these CL spell levels, don't ever try to fry the critters at long range. The spell won't be able to reach any monsters which are far off. Use this spell at this level only to get rid of monsters that are close to you. Very useful if you are surrounded or if faced by King Leoric's army of Burning Undead Captains. This can be very useful even for Warriors and Rogues with only a slvl 4-5 of CL in the Church at Hell difficulty. To get the power of CL at low levels, make sure you have some protection against your back and some monsters are very close to you, then cast. This will ensure a good number of streams with good coverage without fear of getting stun-locked, block-locked or the like. For those with high AC, you don't really need CL here, so get surrounded and cast. You may even notice some CL-gapping even at these low levels (Ed: I have seen CL-gapping at slvl 1 !~!~!) Best casts here include killing King Leoric's entire army bar the King & 1 other by both a Warrior in H/Ch CL slvl 5 and Rogue in H/Ch CL slvl 4.

Medium CL spell levels
This is the range that is most popular among Diablo players. Here you have a good range of monster detection to work with, adequate damage to deal with most monsters, if not in 1 hit then 2 or 3 isn't too bad to arrange as most monsters will succumb pretty quickly. The range extends roughly to the edges of the screen, so what you see is what you hit most of the time. More monsters may be hit when the CL streams travel further through rooms and corridors, hitting monsters as they progress. Watch for them if they don't get zapped in the first cast. The length of the streams may necessitate you to slow down a little between casts. Don't curse this delay, use it to reassess the situation and decide on which action to take next. It isn't always another cast of CL that is next on the to-do list :*)

A lot has been said already about general CL tips for maximum efficiency and usability and I will repeat them here.

i. Keep your streams together. Some monsters will move and if they sidestep into a second stream then they will take more damage.

ii. Keep close to a wall or solid surface. This will soak up any excess CL streams and allow for rapid CL casts just when you need them. It will also limit the directions from which the monsters come at you and on some occasions (see link at the end to YT's demo) the monster behind the wall will actually help to trap some creatures in a sea of sparkling death.

iii. Keep the monsters ahead of you. This will ensure that your CL streams do not go in all directions all over the place and create pandemonium with survival chances about those of winning Bingo at the local church hall on Thursday nights.

iv. Use other spells to help you manage your CL. Use Stone Curse to immobilize moving monsters. Statues don't hit you and are easily targeted by medium CL. Also use Fireball and Elemental where appropriate. Its no use trying to fry 3 dozen Snow Witches when 2 Blood Knights are swinging their swords at you. Teleport is another good spell to use so that you can get all the monsters to 1-2 sides of you instead of being surrounded by them.

v. Use other monsters. Use the Lightning immune monsters to add a few extra streams of CL when they are all in front of you, but refrain from this technique when you are surrounded. This isn't recommended until you are used to high level CL and have a reasonable grasp on CL in general.

High CL spell levels
Nothing new to add here than to say that it is harder to manage than the medium levels, the range of CL is vastly increased to well off the screen. The streams are seemingly endless and casting is very slow, even for Sorcerers. Give any active CL streams plenty of time to dissipate and do their stuff before you cast another lot. This is also what the demo series on YT's website is based on, hopefully with some more text to be added on-site to explain the individual pix. Enter as per link below:-
http://www.geocities.com/TimesSquare/Maze/4747/diablo/clmm01.html
There are forward links through the series, an index is planned.

Conclusion
I'll stop the post here. More can be said and I'm sure more will be said about CL. For now, I hope that this will help some people get more out of the CL spell. I've tried to keep it fairly class-neutral as all classes can use CL for good use, even great use from time to time (my best casts ever were low level CL by Warrior and Rogue).

No co-operative team strategies here, this is for solo players to master CL. Most teams decide on 1 person to use CL, even then sparingly and knowing the other's resistance to Lightning. The positioning must also be good and the enemies' thread great enough to warrant a CL cast, but most of that is best decided by the team in question rather than YT preaching what YT doesn't practices (YT prefers Lightning in co-op play).

Enjoy :*)

Moriah
Date: 01/09/99

- See also a pictorial demonstration at Moriah’s Patch