So I've come across some cards that appear to have effects even when they have been discarded... such as Pentoshi Guildmaster

Response: After you win a challenge by 4 or more total STR, return Pentoshi Guildmaster from your discard pile to your hand. Then, you may pay 3 gold to put Pentoshi Guildmaster into play from your hand.

now I know Im probably just wierded out by this and it actually makes sense but does a guildmaster need to already BE in play for that response to take place? or does his effect essentially still function even when there are no copies of him on the table and he is in the discard pile?

I donno it just seems odd to me... considering that 80% of the time i'd probably forget hes in my discard pile...

thanks in advance!

Actually his ability only works when he is in your discard pile.

Yup. Two general rules to keep in mind here:

1) When a card uses its own name in its ability, the card is considered "self-referential" and can only act on itself. So Guildmaster #1 in play cannot use its Response on Guildmaster #2 in the discard pile.

2) You cannot use the effects on cards that are not in play unless the specifically say you can (like this one, CS-Khal Drogo, or events where it is implied by card type). The fact that this card says to put it(self) into play from the discard pile means it only does something when the card is in the discard pile.

As for forgetting it is in there, yeah, that's a danger. Most people I know turn cards like him 90-degrees to the rest of the cards in the discard pile so they can see they have cards that do stuff from the discard pile at a glance.

Note that if you use his ability and take him back to your hand during the Challenge phase, you can pay 3 gold at this moment to put it into play. You don't have to wait until the next marshalling phase (well it's not frequent to have 3 gold left during the Challenge phase but you can anticipate that).

Just to be complete on this card that can be a bit complicated for new payers .