Playing our first game tonight, and in the last event phase we drew the final red event card. The card required an additional white event card, but we had no white event cards left at this point (they had all been countered in previous rounds). We just ignored it, but I couldn't find any information related to this in the rulebook or in the forums here.
What do you do if a red event requires a white/yellow to be played next, but the white/yellow stack is empty?
This shouldn't be possible. There are 4 white and 4 yellow events, and out of the 8 red events, 4 cause you to draw a white card and 4 cause you to draw a yellow one. (And you will draw only one red card per round.)
Does your deck perhaps have a duplicate red card? Or, were you doing something like re-shuffling red cards?