1st lvl dmg here is 1d10 right? (not 6d10 as it currently states) 

Not sure if you're a grognard attempting to troll or not, but the PHB clearly states 6d10.  Because this spell affects a creature based on current hit points, not hit dice it's 6d10, which is a big distinction from past editions.  Also this spell doesn't allow for a saving throw, which makes it quite potent.

Nope legitimate question, I guess I didn't understand the way it works. I'm a very new DM and my players just had a faery dragon join their party, I'm just trying to stay ahead of them on details in case they have questions.  So if I understand correctly this spell does no damage it only blinds the target creatures and it's starts with the creature with the lowest HP inside of the cone? And then additional other creatures if there's enough left over?

@Funkslinger: that is correct.

It doesn't do damage. 6d10 is right.

Ok but imagine carrying around multi-colored sand. Actually, where would I find it? Would I buy it? And where? Who would carry blue sand?

Probably most wizards and sorcs who cast this spell will just use an arcane focus in place of the sand. That said, in campaigns where my players want to play their spellcasters more flamboyantly and add a bit more flare to an already ostentatious spell (which, without fail, happens any time someone plays a sorcerer) I usually put specialized component vendors in the major metropolitan center of whatever setting I'm using, as well as on-site at any Bard or Wizard schools/colleges/universities.

Quote from Funkslinger >>

1st lvl dmg here is 1d10 right? (not 6d10 as it currently states) 

Quote from Funkslinger >>

1st lvl dmg here is 1d10 right? (not 6d10 as it currently states) 

 It’s not damage you just add the the number you get and compare to the total to the hit points to the target. If it doesn’t go over then nothing happens if it does go over then they get blinded.

This spell strikes me as filling the same sort of roll as sleep...  no saving throw, affect similar (not the same, but similar) HPs worth of opponents (not a lot of HP, but good for affecting a half dozen goblins).  This blinds them for 1 round but affects a few more HP worth of creatures; sleep makes them fall asleep for 1 minute.  Of the two, I think sleep is stronger, but it just depends on the style you want to play.

Low-key an incredible support spell at lower levels. Just place your caster in front of the party, cast at chargin goblins, run away and let your fighters mop up.

I'm taking magic initiate (sorcerer) at level 1 As a variant human paladin. I intend to play her as a tanky Battlefield controller and being able to blind 6d10 hp worth of enemies until the end of my next turn is going to be very useful if my squishies get engaged in melee combat. 

Sleep is so much better though.

I like it just a quick flashbang.

POCKETSAND!!!

No. There is no damage dealt on this spell. 

The 6d10 must be greater than the targets remaining health to succeed.  

Quote from Funkslinger >>

1st lvl dmg here is 1d10 right? (not 6d10 as it currently states) 

 Not sure if you're a troll or not, but here's my honest answer: it doesn't do damage. Instead, it gives creatures the blind effect, which is very useful in combat. So, how this spell works is basically, you're like "I cast color spray!" and then you roll 6d10. You ask the DM "what creature in this 15ft. cone has the lowest hitpoints?" That creature, assuming it doesn't have hitpoints above the score you rolled, is affected, and you subtract its hitpoints from the total. You then move on to the creature with the next lowest hitpoints, and do the same. To conclude, it doesn't do damage, it just blinds, you roll the 6d10 and everything else is explained above.

This spell should also be available to Bard as of Tasha's

Quote from Zoltar99>>

Sleep is so much better though. 

Sleep only affects 5d8 hit-points though so 5-40 or an average of 22.5, whereas Color Spray is 6d10 so 6-60 with an average of 33, so it's a lot more likely to be able to overwhelm several more elite enemies (at lower levels), plus the total hitpoints affected scales faster (2d10 per level as opposed to 2d8).

Another important thing to consider is that the effect of Sleep on a creature ends the moment it takes damage, and so do the benefits of them being asleep. While they'll probably still be prone, if they get a turn before one or more of your allies do then they're going to stand and eliminate advantage against themselves. Being blinded by Color Spray meanwhile lasts for the full round, and includes your next turn, so if you're on your own you're guaranteed to get the full benefit vs. affected creatures, but so are all your allies if you're not alone.

So personally I think they're pretty balanced; I see Sleep more as a stealth aid, i.e- put guards to sleep, or ensure that already sleeping enemies do not wake as the party are sneaking past. Color Spray is more like a panic button to escape/hide or a force multiplier to give advantage for the entire party against your target(s).

No saving throw!  Potent on an Arcane Trickster.  Use immediately before using your Cunning Action to Dash past a squad of guards.  Zip around a corner, and make a Stealth check to move past them silently.  This will keep the guards from looking behind them or walking around the corner when the effect ends.  It's also great for making a getaway.  

SAND IN THE EYES!

YOU’LL NEVER GET MY PLANS!