Mythic rares appear 10% of the time
It's an excellent combo piece that has playability across Modern, Pioneer, Standard, and Commander
Unlike traditional card draw, you arent accumulating lands at a faster pace as well when learning, so the typical churn where drawing more cards gives you more spells and the resources to cast them is absent
It's on the Game Changers list for a good reason
I don't know if you have played your deck yet (as BLB card are not released yet), but I think your deck has a bit lack of ramp/land (I may be wrong, as you have some good mana dorks and treasure creation)
Once the early game has been locked down, though, Ugin's Labyrinth can also be the last card needed to close the door