Foulborn Exalted Orb

Foulborn Exalted Orb adds one new random modifier to a rare item, with the roll weighted so that higher level modifiers come up more often. That weighting is the whole point: a regular augment treats every tier alike, this one does not.

Right click the orb, then left click the rare item you want to augment. The target does not need to be uninfluenced, but it still cannot exceed six random modifiers in total.

The orb is birthed from the Genesis Tree from a Lavish Wombgift, which makes its supply a by-product of how deeply players are engaging with that mechanic rather than of any boss rotation.