Let's imagine that, by some card manipulation(it seems possible in Legacy if you give him the Martell affiliation), I have a Corrupt Contender that cannot be discarded from play. Can I trigger its effect?

Card Text:

Lannister character, Cost 3, STR 2 MIL INT

Knight. Ally.

Challenges : Corrupt Contender gains +10 STR until the end of the challenge. After the challenge resolves, discard Corrupt Contender from play (cannot be saved). Limit once per challenge.

The FAQ states that "cannot" prevents choosing a card as the target of an effect in addition to using the card to pay a cost, but says nothing about non-targeted effects.

I would say yes, you can. Since it's not a cost and the discard effect is independent I don't see a problem.

Correct. Discarding is not a target requirement, so you are allowed to initiate the effect. The "cannot be discarded" then stops the discard part from happening.

Look at it this way: if "cannot be discarded" stopped you from initiating a general, non-targeted discard effect, one Knight of the Rainwood on the table would stop all players from being able to play Westeros Bleeds at all - instead of being able to play it and watching all other characters except the Knight be discarded.

Also keep in mind that if you were to use Corrupt Contender's ability, and THEN before he would be discarded you somehow gave him "cannot be discarded", there would be no way for the ability to know that when it was being initiated.

Thanks for the replies.