Earlier quoted context omitted.
Well. You can have as many cards as you like, but still just 4 copies of any card, apart from basic lands. So there's very little benefit to having 200 cards in your deck.
No benefit except that it is awesome. http://gatherer.wizards.com/Pages/Card/Details.aspx?name=bat...
444 Shadowborn Apostle
1 Reaper from the Abyss
1 Sire of Insanity
2 Griselbrand
4 Cavern of Souls
214 Swamp
There are probably better lists but I like the simplicity of this one and the 666-card deck.
Source: http://www.channelfireball.com/articles/frank-analysis-is-pl...