The Obol Gambling Tool is incredibly useful because it tells you which items to target at the Purveyor of Curiosities to get the legendary aspects you want. In Season 5, it even works with Uniques!
How Does it Work?
Certain classes have more or less Uniques in their pool for a given item slot. Logically, the class with the fewest uniques will have the highest chance to roll the Unique you need, and vice-versa. Some classes and item slot combinations have fewer possible Aspects to roll.
Let’s take 
X’Fal’s Corroded Signet as an example:
| Class | # Unique Rings | # non-Mythics | Odds to get X’Fal |
|---|---|---|---|
| Barbarian | 5 | 4 | 25% |
| Necromancer | 5 | 4 | 25% |
| Sorcerer | 5 | 4 | 25% |
| Rogue | 6 | 5 | 20% |
| Druid | 7 | 6 | 16.67% |
As you can see above, it’s not advised to gamble on Druid or Rogue to get that specific unique, as the optimal class options are Barbarian, Necromancer, and Sorcerer.
Head over to Diablo4.life to use the gambling tool to target your Aspects and Uniques!
Reddit user GGM also created a video covering the tool and you can watch it below!
Source: Reddit