Do all 4 targets(the initial and the 3 it leaps too) all take 10d6 damage? Or just the initial one

This spell provides a good reason to dip 2 levels in Tempest Cleric as a sorcerer or wizard.  Using Destructive Wrath, you can deal 80 lightning damage on a failed save, or 40 damage on a successful one.  

Wait, is it just me or is this not actually that great of a spell? I mean don't get me wrong, it's not a bad spell whatsoever, it just feels like more of a 5th level spell. It's more flexible than other multi-target spells, but it's maximum potential is much lower than something like fireball, otiluke's freezing sphere, or even things that are a little more reasonable like cone of cold or ice storm, and it doesn't deal much more damage. It does have a slightly better damage type. 
I don't know, what do you guys think, should it be 1 level lower, deal a bit more damage, or target 1 more person?
Or is it fine as it is and raw potential damage is just what it loses for being so easy to use?

@ShaydyCharacter,

To me, this is more of a villain spell.  Players, where possible, tend to spread out past the first line of fighters.  The casters are usually as far back from the front line as they can get and be in range.  This spell can allow you to hit spread out targets where only two or three would be under the fireball.

@OrionPeace
And without nuking the minions too. I guess you're right. Well, even for the players it's more reliable than cold of cold, so I guess it's fine as is. 

POWER!!!!! UNLIMITED! POWAAAAHHHHH!!!!!

Ok, so noone asked the most important question yet... it has a single initial target and it's additional effect is the one, that picks up the extra targets... can it be twinned?

Another question not adressed here is the logic of the spell. If any other creature would be standing in straight lines between the chosen targets and the lightnings path between them, wouldn't they be hurt too? I know that's not the rule, but it would make the spell make more sense.

The fact that my Tempest cleric does not get this spell is deeply upsetting

the absolute strongest DM spell for 11th level casters and above. The target options include objects, so chain lighting destroys PC gear without a save being involved, and does a ton of damage. Its better than Disintegrate. 

Would this spell work with warcaster reaction?

Quote from Alethalion >>

Would this spell work with warcaster reaction?

I would say no, it shouldn't, since it seems pretty clear the intent of the War Caster opportunity attack thing is that you should only be able to cast spells that only affect the one creature that triggered the opportunity attack. A very strict literal wording could lead one to conclude that this spell only actually "targets" one creature, though, so I suppose it's up to the DM to decide.

What's the actual Dex Save that has to be rolled to save vs spell though? It doesn't have what one is supposed to rolled for some reason.