If Cinccino uses "Amazing Plea" and there are zero cards in the discard pile, do I automatically do 80 damage? Or what if I only have one card in the discard pile?
The answer is the same regardless of the number of cards in the discard pile. Your opponent decides whether you take the cards (even if it's 0) or do 80 damage.
Source: Crimson Invasion FAQ (2017-10-20), TPCi Rules Team (2017-11-02)