Coolest plane for this item?
Theros.

Astral plane is basiclly time stop soo... it's pretty hard to use in neither sittuations

Amazing item, one of my favorites other than the chronolometer. However the wording confuses me. It says you use the star pulled off to cast Magic Missile. Since I’m casting the spell with the star, would I also be able to cast say Misty Step as a bonus action?

Casting a spell with a magic item still counts a casting a spell, which still imposes the 1 leveled spell per turn limit RAW.

This is also an amazing Magic The Gathering card. 

That's not a bug, for magic missile you roll 1 die, and all missiles deal that damage as the missiles happen simultaneously. It's an obscure rule that doesn't apply to many other spells.

Hey there's a bit of a bug with this on the site! If you add it, the magic missile spell will only show up under 1st level spells, instead of 5th level.
I fixed it by cloning it to a homebrew item and changing the "min-max" section of the magic missile spell details section to nothing in the min section and 1 in the max section, then setting "cast at spell level" to 5. The spell shows up in the correct spot along with other 5th level spells and uses the right amount of charges!

Is it possible to gives the stars to team mates to use if the owner of the robe of stars gives it to them?

Also can you pull multiple off out of combat and thrown them all at once?

got both this and the ring on my fighter and its friking overpowered

Does this use your spell action, or if you hasted could you use your Haste Action since its eating an "action" (you can use an action to pull of)?

Item isnt working right this the level 5 spell/charges....

If I use the Robe of Stars to enter the Astral, will I always arrive at the same location? If so, could I use the Astral Plane as a temporary storage space?

I will dominate flying monsters know