Very simply, it makes the main parts of their effects unable to work. The Cage's ability means that if an effect would try to move a creature card from a library onto the battlefield, instead that card stays in that library.
101.2. When a rule or effect allows or directs something to happen, and another effect states that it can’t happen, the “can’t” effect takes precedence.
Example: If one effect reads “You may play an additional land this turn” and another reads “You can’t play lands this turn,” the effect that precludes you from playing lands wins.
"Creature cards in graveyards and libraries can't enter the battlefield." on Grafdigger's Cage does what it says.
Collected Company:
Look at the top six cards of your library.
That's what it says, that's what you do.
Put up to two creature cards with converted mana cost 3 or less from among them onto the battlefield.
You can't put any creature cards from the library to the battlefield, so you don't.
Put the rest on the bottom of your library in any order.
Since you moved none of them, the "rest" is all of them.
Eldritch Evolution
Search your library for a creature card with converted mana cost X or less, where X is 2 plus the sacrificed creature's converted mana cost.
That's what it says, that's what you do.
Put that card onto the battlefield, then shuffle your library.
101.3. Any part of an instruction that’s impossible to perform is ignored. (In many cases the card will specify consequences for this; if it doesn’t, there’s no effect.)
You can't put that card onto the battlefield, so you don't. You still shuffle your library, though.
Exile Eldritch Evolution.
That's what it says, that's what you do.
Private Mod Note
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Why bother with mere rulings when so many answers can be found in the Rules?
Thanks for the responses. Grafdigger's Cage works as I imagined it would, but I know it's a somewhat troublesome card from a rule's perspective, and a few of my friends were issued incorrect rulings regarding the Cage at a high level event they recently attended. Just wanted to make sure that my understanding of the card was correct.
Private Mod Note
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WUBRGMr. Bones' Wild RideGRBUW Trap your friends in an endless game with this 23-card combo!
It can be difficult when trying to simply use your intuition, because the physical actions you take with your cards are very similar between something like Primal Surge and Genesis Wave, but one of them is affected by Grafdigger's Cage and one of them isn't.
Trap your friends in an endless game with this 23-card combo!
I̟̥͍̠ͅn̩͉̣͍̬͚ͅ ̬̬͖t̯̹̞̺͖͓̯̤h̘͍̬e͙̯͈̖̼̮ ̭̬f̺̲̲̪i͙͉̟̩̰r̪̝͚͈̝̥͍̝̲s̼̻͇̘̳͔ͅt̲̺̳̗̜̪̙ ̳̺̥̻͚̗ͅm̜̜̟̰͈͓͎͇o̝̖̮̝͇m̯̻̞̼̫̗͓̤e̩̯̬̮̩n͎̱̪̲̹͖t͇̖s̰̮ͅ,̤̲͙̻̭̻̯̹̰ ̖t̫̙̺̯͖͚̯ͅh͙̯̦̳̗̰̟e͖̪͉̼̯ ̪͕g̞̣͔a̗̦t̬̬͓͙̫̖̭̻e̩̻̯ ̜̖̦̖̤̭͙̬t̞̹̥̪͎͉ͅo͕͚͍͇̲͇͓̺ ̭̬͙͈̣̻t͈͍͙͓̫̖͙̩h̪̬̖̙e̗͈ ̗̬̟̞̺̤͉̯ͅa̦̯͚̙̜̮f͉͙̲̣̞̼t̪̤̞̣͚e̲͉̳̥r͇̪̙͚͓l̥̞̞͎̹̯̹ͅi͓̬f̮̥̬̞͈ͅe͎ ̟̩̤̳̠̯̩̯o̮̘̲p̟͚̣̞͉͓e͍̩̣n͔̼͕͚̜e̬̱d̼̘͎̖̹͍̮̠,͖̺̭̱̮ ̣̲͖̬̪̭̥a̪͚n̟̲̝̤̤̞̗d̘̱̗͇̮͕̳͕͔ ͖̞͉͎t̹̙͎h̰̱͉̗e̪̞̱̝̹̩ͅ ̠̱̩̭̦p̯̙e͓o̳͚̰̯̺̱̰͔̘p̬͎̱̣̼̩͇l̗̟̖͚̠e̱͉͔̱̦̬̟̙ ̖͚̪͔̼̦w̺̖̤̱e͖̗̻̦͓̖̘̜r̭̥e͔̹̫̱͕̦̰͕ ̗͔̠p̠̗͍͍̱̳̠r̰͔͎̰o͉̥͓̰͚̥s̟͚̹̱͔̣t͉̙̳̖͖̪̮r̥̘̥͙̹a͉̟̫̟̳̠̟̭t͈̜̰͈͎e̞̣̭̲̬ ͚̗̯̟͙i͍͖̰̘̦͖͉ṇ̮̻̯̦̲̩͍ ̦̮͚̫̤t͉͖̫͕ͅͅh͙̮̻̘̣̮̼e͕̺ ͙l͕̠͎̰̥i̲͓͉̲g̫̳̟͈͇̖h̠̦̖t͓̯͎̗ ̳̪̘̟̙̩̦o̫̲f̙͔̰̙̠ ̹̪̗͇̯t͖̼̼͉͖̬h̹͇̩e͚̖̺̤͉̹͕̪ ͚͓̭̝̺G͎̗̯̩o̫̯̮̟̮̳̘d̜̲͙̠-̩̳̯̲̗̜P̹̘̥͉̝h͍͈̗̖̝ͅa͍̗̮̼̗r̜̖͇̙̺a̭̺͔̞̳͈o̪̣͓̯̬͙̯̰̗h̖̦͈̥̯͔.͇̣̙̝
It interacts in accordance with this Golden Rule:
"Creature cards in graveyards and libraries can't enter the battlefield." on Grafdigger's Cage does what it says.
Collected Company:
You can't put that card onto the battlefield, so you don't. You still shuffle your library, though.
Trap your friends in an endless game with this 23-card combo!
Edit: Corrected card name
Two Score, Minus Two or: A Stargate Tail
(Image by totallynotabrony)
RULES OF MAGIC :
http://magic.wizards.com/en/game-info/gameplay/rules-and-formats/rules
Two Score, Minus Two or: A Stargate Tail
(Image by totallynotabrony)