Like most poorly written rogue archetypes, it provides you an easy way to double down on sneak attacks. Use your bonus action for a playing card gambit (75% chance to sneak attack if you hit) then use your action to attack, and sneak attack again. You can only sneak attack once per turn, but the gambit isn't technically a sneak attack, it's just an attack that uses the same amount of dice as your sneak attack. It also specifies that you can't use it if you already used your sneak attack dice on that turn, but nothing prevents you from using your sneak attack dice after the gambit.

The other archetypes have similar issues. Good ideas, but whoever wrote these doesn't know what they're doing, doesn't know how to write the mechanics in a way that doesn't break anything.