The Gambler is a divination card. A set of five can be exchanged for a divination card chosen in a weighted random fashion. It is more likely to return a common divination card like Her MaskHer Mask4Sacrifice FragmentTo her beauty you submit, lest your neck the great Queen slit. than a rarer one like The DoctorThe Doctor8Headhunter"They said I needed my head examined, but I'd rather just take yours." - Klopek the Cannibal. The outcome of the exchange can be any divination card including the Gambler itself, and because the Gambler is a fairly common divination card, it is not that improbable to turn in a set of the Gambler only to get a single one back.
The Gambler has restrictions on where or how it can drop.
Can drop from any map area. Has a minimum drop level restriction of 68 Equivalent to T1 maps..
(Undocumented in patch notes) This card's drop level requirement was changed.
Drop weightings and minimum area levels for the vast majority of cards have not been changed, but drop weightings for a very small number of cards have been reduced in cases where the number of maps they're available from has greatly increased.
A longstanding bug in the code determining area level restrictions for some divination card drops has been fixed. This means that cards intended to have a high area level requirement (mostly ones that grant item level 100 items) will no longer fluctuate wildly in availability from league to league.