Name:Restrict and Restrain
Type:Event
Expansion set: Mask of the Archmaester
Affiliations(s): Lannister
Text:
HL only. Play before any challenges have been initiated this phase. Any Phase: Kneel a Learned character to have each player choose up to 3 characters. Characters not chosen cannot participate in challenges this phase.

If I play this event, can my opponent choose his Red Viper as one of 3 characters? If not, does that mean Red Viper can not participate in any challenges in this phase?

Uncle Joker said:

Your opponent cannot choose his Red Viper as one of the 3 characters because the immunity to events prevents it. However, that same immunity to events lets the Viper ignore the "cannot participate in challenges" effect that the event places on characters not chosen.

The event does not affect the Viper and your opponent will have 4 characters that can participate. The mechanics are different, but the end result is like playing Wildfire Assault when your opponent has "cannot be killed" characters in play.

It is clear now, thank you.