It has previously been ruled for Ikoma Ujiaki, that if all of the cards in a province are faceup, the pre-Then aspect of his ability does not fully resolve, so he cannot attempt to put cards into play.

Based on that, if the opponent of Aranat's controller elects to not reveal any provinces, does the pre-Then fail to resolve?

On 3/27/2019 at 2:41 PM, Bayushi Shunsuke said:

It has previously been ruled for Ikoma Ujiaki, that if all of the cards in a province are faceup, the pre-Then aspect of his ability does not fully resolve, so he cannot attempt to put cards into play.

Based on that, if the opponent of Aranat's controller elects to not reveal any provinces, does the pre-Then fail to resolve?

Because this is a “may” ability, the post-Then effect can resolve even if the pre-Then effect does nothing (as the opponent elected to not do it).

[Tyler Parrott, Mar 13 2019]

Due to the removal of the "Then" rules, this ruling is no longer relevant, or required.