How do cards like living wish and Spawnsire of Ulamog work in EDH? Can I just take cards from my collection or what? And if I already have a copy of the card in my deck, can I get another from outside the game?
In a sanctioned event, a card that's "outside the game" is one that's in your sideboard. In an unsanctioned event, you may choose any card from your collection.
So far as I am aware, this holds for EDH as well: if you're using sideboards, the "outside the game" cards are those in your sideboard. Otherwise, they're whatever you have with you in a trade binder / box / etc.
If I remember correctly, the ruling on this not long ago was that EDH decks are allowed a 10 card sideboard, for wish purposes as well as eldrazi's. These are merely functional basis cards that you might only need against certain types of decks. (my memory could be failing me though, couldn't find the article)
There's actually been a recent addition to the official rules to handle cards outside the game. The new rule is that "wish" effects do nothing unless playing with the optional sideboard rule. If you are using the optional sideboard rule (which you should agree to before the game), your sideboard (of up to 10 cards) must conform to the same rules as deck construction--no multiples, no repeating cards that are already in the maindeck, and no off-color cards.
There seems to be some confusion over the wish rules, so I'm just going to go through them all.
Quote from MTG Comprehensive Rules »
400.10. An object is outside the game if it isn't in any of the game's zones. Outside the game is not a zone.
108.3b. Some spells and abilities allow a player to take cards he or she owns from outside the game and bring them into the game. (See rule 400.10b.) If a card outside that game is involved in a Magic game, its owner is determined as described in rule 108.3. If a card outside that game is in the sideboard of a Magic game (see rule 100.4), its owner is considered to be the player who started the game with it in his or her sideboard. In all other cases, the owner of a card outside the game is its legal owner.
So, according to the comprehensive rules, in any game, you can get any card that you legally own that is in your sideboard or not in any of the game's zones. Remember, if you are playing in a format in which some sets or cards are not permitted, you can't wish for them because they are not permitted in the game at all.
So you can get any card, even off-color hybrids or a second copy of a card already in your deck, from your collection to use. You can even get the card if it would cause you to have more than 4 copies of that card in the game (or more than 1 in a highlander format). Even if you are playing with a sideboard, if it is a non-sanctioned game you can still get cards from your collection too. Within the limits of being reasonable to the other players that is. They may just kick you out of the game if you want to drive home and search through boxes and boxes of cards.
Quote from MTG Floor Rules »
Players may not refer to outside notes during games.
Players may look at their own sideboard during a game as long as the sideboard remains clearly distinguishable from other cards. The sideboard must be clearly identified and separated from all other cards in the play area.
It is part of the Magic Tournament Floor Rules that in a sanctioned tournament, you are not permitted to reference outside notes during a game, so you cannot get cards from your collection. Since players can look at their sideboard during a game, wishes can get cards from your sideboard in sanctioned tournaments. If you do not have a sideboard in this case, you cannot find any cards with wishes.
It is possible (and very likely) that any local non-sanctioned EDH tournaments have similar restrictions, so you will likely be restricted to wishing for cards from your sideboard during a tournament. Remember, your sideboard and decklist together must satisfy all deckbuilding constraints, which is why many people say you may not be able to wish for a second copy of a card in your deck (which is not strictly a rule).
That is how wishes have always worked in any format without wish-specific rules, including EDH until recently.
Quote from dragonhighlander.net EDH Rules »
15. New: Abilities which refer to other cards owned outside the game (Wishes, Spawnsire, Research, Ring of Ma'ruf) do not function in EDH unless the optional sideboard rule is in use. If sideboards are used, wishes and similar cards may retrieve sideboard cards.
For some reason, the EDH council decided that the comprehensive rules weren't good enough and added this format-specific rule. If you are using this set of rules, your wishes just don't function without a sideboard. I guess you can still play them if you want, they just won't find anything.
I cant believe this thread! EDH is about having fun, if you plan Spawnsire in EDH, fun is playing 20 mana and dropping a buttload of cards onto the field, boring is going through a carefully preplanned sideboard and only putting a few. Sure you can listen to the "official" rules, but I would highly recommend your playgroup ignore them and just "wish" for whatever you want.
NOTE: Seriously though? Sideboard in an EDH game, wtf is wrong with people?!?!!?
The sideboard rule is there for EDH tournaments. EDH is a "casual" format, but some rules are needed for tournaments. If you have a problem with a ruling in a casual format then your playgroup is welcome to do whatever they want, but in a tournament setting you can't wish up your entire binder.