What would the effect be if the opponent had a Darksteel Colossus in their deck?
A draw? Reshuffling DSC over and over every time it shows up? I got this combo against a Doomsday player that might very well have had a DSC in it.
I actually cover this in my article, which may or may not have been where the combo comes up.
Darksteel Colossus has two replacement effects trying to apply to it, Leyline of the Void's and its own. Its controller will choose which replacement effect applies to it. So they can choose to shuffle it back into their library. However, it will eventually be milled (you'll even eventually end up with DSC as the only card in the library). Its controller can keep choosing to shuffle it back into their library as many times as they want, but eventually in order to not have the game draw, they have to let it be removed from the game. It's only a draw if it's a loop with all non-optional actions. If you have a way out of the loop, eventually you have to take it, or you're stalling. This is the same reason why you can only draw the game with Animate + Worldgorger Dragon if you have no other creatures in the graveyard.
What about without Leyline out? What happens if I have Helm out, use it on my opponent, and the first card it flips is Darksteel Colossus? Do I get the DSC or, since the DSC has a replacement effect and Helm specifically says 'put into that graveyard' then I just keep on flippin?
Darksteel Colossus has a replacement effect, so it will never go to the graveyard (this is in fact how the combo works). So you will keep putting cards into their graveyard, and the Colossus will not even count towards X cards.
