I was playing Trial of Ambition and had Ajani set as my White node planeswalker, with a custom event deck built already. I did not have a Black node planeswalker set yet. When I went to set my Black node planeswalker as Nicol Bolas, the Ravager, it also changed my White node planeswalker.
@Tombstone No, but I imagine it is similar to how people exploit to switch Planeswalkers in other events.
To note, my first match with NB2 on White was a level 60 enemy (because my Ajani was at LV60). All subsequent matches were based on NB2’s level. The Black node played as normal.