MTG cards that are crazy broken or unfair?

I've heard about a lot of things described like that, so I began to wonder how good the ones i hadn't heard of are. I've heard of tinker being broken, Library of Leng being crazy, Phage, Nemesis of Reason, etc. Some of you may not think tinker and Phage are on the same level, but they are if you have something worth pulling out(darksteel forge, darksteel colossus, etc.). The point of this question is not really what are the crazy broken things like phage, but what have you figured out, done, seen, that just made you say "That is bullshit, thats so broken". I personally hate the card shimmer for example but anyway i'm rambling now so just tell me what you think.