When can Palps change dice? From the text it seems like any time but does he have to change only during the modify dice step? Or can I roll dice, see what my opponent rolled then change a dice if needed when attacking? His game text mentions nothing about attacking or defending so I'm of the mind that Palps is anytime you want.

Attacker rolls dice

Defense modifies

Attacker modifies <--palp

Defense rolls dice

Attacker modifies

Defenders modifies <--palp

Compare

When can Palps change dice? From the text it seems like any time but does he have to change only during the modify dice step? Or can I roll dice, see what my opponent rolled then change a dice if needed when attacking? His game text mentions nothing about attacking or defending so I'm of the mind that Palps is anytime you want.

Palpatine's modification of dice is a die modification that can happen outside of combat.

In-combat, it's still a modification of dice.