Pocket Sand....Sh Sha!

oh baby this is cool

Very nice for rogues because of cunning action.

Invisibility into bonus action hide.

Sand in the eye!

So, you can get greater invisiblity for an entire combat from an uncommon item. pretty gnarly.

It's actually just treated as the Invisibility spell, not Greater Invisibility. It states "If a creature affected by the dust attacks or casts a spell, the invisibility ends for that creature."

Quote from summussum >>

So, you can get greater invisiblity for an entire combat from an uncommon item. pretty gnarly.

 

 Nope, greater invisibility keeps you invisible even through an attack.  This does not.

What happens if you get covered in water after you use the Dust? Does water, like rain, wash off the Dust's magical effects, or once used, does it still work just fine?

 and the dust is consumed when its magic takes effect.

From how it's phrased, I personally read it as the dust no longer existing once it turns you invisible. Also it only mentions the invisibility ending when the creature attacks or casts a spell, so RAW it works just fine even if you get covered in water, unless as a DM you want to treat it as an object that attaches to you and only grants you invisibility as long as there is still dust on you, therefore allowing the invisibility to be affected by washing the dust off.

No, invisibility drops if you attack or cast a spell.

Sounds like a DM call.