Nemesis introduces "Expert Dice", which may be used as normal dice, or the player can select their value before the roll, but no two Expert Dice can be selected to have the same value. Expert Dice are also used as buffer against die penalties, where each Expert Die counteracts one die penalty, but then must be rolled as a normal die.
The introduction of "Expert Dice" by Nemesis allows players to customize their dice rolls or use them as a buffer against penalty effects.  Each Expert Die can offset one penalty but must be rolled normally after the counteraction.