If Red Viper is the only character in play controlled by my opponent. In the meanwhile, I buy House Umber Berserkers into play, does my opponent need to kill Red Viper? I guess he might need to because although Red Viper is immune to character abilities, however this card seems to not targeting Red Viper. It's because my opponent doesn't have other character to kill, he must kill Red Viper then.

Am I getting this right? Please correct me if I'm not.

"A card with immunity ignores the effects of card types to which it is immune."

The effect that would cause him to kill the Red Viper is a characters ability so his immunity would cover that.

Immunity is not suspended just because you don't have any other characters that the effect could work on. Immunity says that not only can the character not be targeted by those kind of effects but that the character completely ignores the effects targeted or not. So The Red Viper can not be killed by the berserkers just because there are no other characters on that opponents side of the field. The Viper simply ignores the character ability.

@ktom: Am I mixing things up, or is TRV not even a legal target for the effect of House Umber Berserkers (which would be relevant if I have other characters besides The Red Viper in play, in which case I would be forced to choose a character other than TRV)?

Saturnine said:

ktom is correct I think. RV is immune, so he ignores this ability regardless...

Saturnine said:

I'm not ktom, but I feel qualified to answer anyway . The FAQ tells us that "A card cannot be chosen as a target of effects to which it is immune", and that should cover this case.

Ratatoskr said:

That was my thinking. But ktom usually goes out of his way to make sure all possible misunderstandings are cleared up, which he didn't do here, so I got confused.

Saturnine said:

Maybe he's got better things to do for once. Or maybe he's slipping.

The original post mentions something along the lines of "even though the Viper is immune, since he's the only choice, I pick him anyway, right?"

That's what I was going after with my post, pointing out that:

A) You don't get to forget about immunity just because there isn't another card to hit.
B) You cannot target the immune character.
C) Even if you could, it wouldn't matter.

So everything I said was in line with what you know and understand, Saturnine. My expansion to your "cannot target" was the "and it wouldn't matter if you could" part. People always seem to forget about that part of immunity, concentrating instead on the inability to target. So I was pointing out that while the logic behind "can't choose anyone else, so the fact that the Viper os alone gets around his immunity and I can choose him" is indeed wrong, even if it wasn't, he still wouldn't die.