The Bounty Hunter bonus round rule is one of the many rules that can be applied during the Bonus Round episodes. It generally spawns around floor 4 or 5 for all characters and is pretty common at that level. This rule will not show up if the Singer bonus round rule is active.

Bounty Hunter

You will never roll a 6.

When the rule activates, the player is prevented from rolling a 6 with your initial roll. This includes natural dice rolls at the start of your turn, dice calculated by the Robot's CPU counter, and the dice requested with The Robot bonus round rule.

The enemy is not affected by this rule and is always able to roll a 6.

In order to roll a six, you will have to roll it through other forms of equipment, like Spatula to flip a 1, or Combat Roll to reroll a dice into a 6.