Using higher level spell slots looks like they go a long way here compared to other spells. It not only increases damage, but increases the chance of the orb bouncing and the amount of bounces.

if you cast this at 7th level or higher, the bounce is GUARANTEED to happen since you are rolling 9d8+

Quote from RealLacrum >>

if you cast this at 7th level or higher, the bounce is GUARANTEED to happen since you are rolling 9d8+

 

 Oh yeah It can!! And It can bounce up to 7 more times, meaning 8 different attacks (counting the inital attack). And since there is no limitations on bouncing to a target that has already been bounced at least once, you can easily bounce it between two targets to rack up a lot of damage.  Chromatic Orb Pinball, anyone?

Why is this spell not available for a custom weapon addition?

Quote from TheWildMeek >>

Why is this spell not available for a custom weapon addition?

 What do you mean by that? Are you trying to add this spell to a sword or something?

I absolutely can't wait for chromatic pinball, love it!

Chromatic Orb + Elemental Adept: Fire + Flames of Phlegos = more bounces 🔥

Add Spell Sniper to ignore cover and attack enemies adjacent to you

Unfortunately you can't have it bounce and hit the same creature multiple times

"The orb can leap a maximum number of times equal to the level of the slot expended, and a creature can be targeted only **once** by each casting of this spell."

Tbf though, it might have not had that line at the time when you read it and was fixed later (dndbeyond has had a few errors like that happen with the new book).

6th level actually.  Since it starts at 3d8 and adds one per level.  

SInce it is also basically impossible for it NOT to bounce at 6th level.  Since the odds of rolling 1,2,3,4,5,6,7,8 on 8d8 are roughly 1 in 17 million

In the "Using a higher spell slot" section :The orb can leap a maximum number of times equal to the level of the slot expended, *and a creature can be targeted only once by each casting of this spell.*

So unfortunately it does have that restriction, but still, that's a lot of damage to multiple targets.

How large is the orb?

Quote from TheWildMeek >>

Why is this spell not available for a custom weapon addition?

 To achieve that, you'd want to homebrew an item (whatever kind of weapon you want to use) that allows the wielder to cast this spell (usually limited to a number of times per day)

Quote from Elgoblino10986 >>

How large is the orb?

 If the orb's size was mechanically important, its size would be included in the spell. I, however, always think of it as being about the size of a softball.

Quote from Princedg5678 >>

Quote from RealLacrum >>

if you cast this at 7th level or higher, the bounce is GUARANTEED to happen since you are rolling 9d8+

 

 Oh yeah It can!! And It can bounce up to 7 more times, meaning 8 different attacks (counting the inital attack). And since there is no limitations on bouncing to a target that has already been bounced at least once, you can easily bounce it between two targets to rack up a lot of damage.  Chromatic Orb Pinball, anyone? 

 " and a creature can be targeted only once by each casting of this spell." So no pinball.

Sorcerer Rage aka innate Sorcery, plus empowered meta magic = great success. 

Innate Sorcery gives advantage on attack rolls made with spells and empowered meta magic only cost 1 Sorcery point to reroll damage die up to charisma modifier. If no duplicates i reroll 1-4's for a mere 1 Sorcery point. 

I play a control Sorcerer and this is like my only damage spell and I have no complaints(leveled spell, not including cantrips). I used to twin it with old rules, but now...........

Line ‘em up and knock ‘em down…

People points out that up casting it to 7th level or above guarantees bounces since you'll always roll at least one pair with 9d8
.... I'd like to add that it can be done even earlier if you have feats/features that lets you reroll low damage numbers of specific damage types (which you choose with this spell), reducing the number of outcomes thus increasing the likelihood of pairs
(or one could keep the 1s if it makes it bounce instead of rerolling them)

Quote from Princedg5678 >>

Quote from RealLacrum >>

if you cast this at 7th level or higher, the bounce is GUARANTEED to happen since you are rolling 9d8+

 

 Oh yeah It can!! And It can bounce up to 7 more times, meaning 8 different attacks (counting the inital attack). And since there is no limitations on bouncing to a target that has already been bounced at least once, you can easily bounce it between two targets to rack up a lot of damage.  Chromatic Orb Pinball, anyone?

 Except that there is a limitation against hitting the same target twice.

Using a Higher-Level Spell Slot. The damage increases by 1d8 for each spell slot level above 1. The orb can leap a maximum number of times equal to the level of the slot expended, and a creature can be targeted only once by each casting of this spell.

I need to figure out if I can twin spell this now that it can potentially target multiple enemies… 

There are two limitations to the 'hit 8 targets/bounce 7 times' rule. First, you need to make a successful attack roll for each new target. Second, you cannot target a creature twice.