Dimensional Cube Lucky rooms

What is the chance of lucky room in Dimensional Cube?

I have done 10 now without getting a single one?

Also What are the rewards, do you get many solars?

Tooki = 200-300k silver
Devil = 3 TIMES the honing rewards of a regular cube.
Chest = 3 books from purple to legendary.

I have no idea of the odds sometimes its like 3 out of 4 runs, sometimes its 0 out of 12 cubes.

I got a teammate that did get all 3 in a single run soooooo…