When casting one of the adversaries, I have only experience with intrepid adversary, it doesn't ask "how many times would you like to pay the additional cost" on etb.
Treat this like x=1,2,3 or confirm 0. And then show full cost of the desired cost. A

As of now, It just has an "auto tap" button.

Twice It prioritized using ww to pay for the cost, and even when floating 2ww, it left 2 colorless in my pool.