The USEPWiki says that the adept spell Chain Lighting "Does 40 points of shock damage to Health and half to magica, then leaps to a new target." It says the expert spell Thunderbolt "Does 60 points of shock damage to health and half that to magica." Granted it does 20 points more damage, but it seems to me that the Chain Lightning might be more powerful because it jumps to a new target. Am I missing something? Is the Wiki wrong?

The wiki is never wrong, but M'aiq agrees, chain lightning is much more better.

the wiki is never wrong, though id say it depends on your needs for battle and your charachter type chain lightnings better in the long run in terms of battle set up and getting off as much damage to as many enemys on screen as possible yknow.

What are the magicka costs for both of the spells...?

Chain Lighting.

I would reccomend outfitting your followers with shock resistance so you can use them as a conduit

Thunderbolt is more powerful, but only at a single enemy. Chain Lighting can hit multiple foes at once and has a cheap cost.

90 in Destruction, Expert Perk.

Chain Lightning cost 37 Magicka.

Thunderbolt cost 81 Magicka.

This is why We say Destruction is broken

^ This a good explanation.

Thunderbolt can be difficult to cast multiple times in a row, because it uses up a lot of magicka.

Say hello to 4x25% item magicka reduction.

No cheating, no [censored].

You can easily raise that 40 to 60 with the damage perks. Idk about Thunderbolt

You can raise it to 90.

And not in the good way, either

Also keep in mind that chain lightning will hit your allies too. Only reason why i dont use it.

This is why I use thunderbolt.

I prefer thunderbolt. Just enchant for destruction reduction. That way you can blast away and not destroy your summoned minions or allies

Storm Thralls never complain about being hit

Those of Us that have the Dragonborn DLC do not need to care about hitting Followers Minions. Shockingly the Island of Solsthiem can allow a Mage to exploit a given Element to the fullest Potential.