I'm not sure you get it right, but Sidisi, Brood Tyrant only nets maximum of one zombie per trigger. Therefore quantity of triggers > depth of mill. Following that, I'm not so impressed with the Mirror-Mad Phantasm's function in this deck as you are. Mirror-Mad Phantasm is more like Hermit Druid in decks where you want to dump your library into your graveyard for some shenanigans (like Dread Returning a combo piece).

Also I see you are a fan of fast paced games, since you are putting yourself on the clock with Dark Tutelage, when there are so many better options in blue (Rhystic Study) and black (Phyrexian Arena) that doesn't cost you up to eight life. Of course Dark Confidant is played almost in every competitive deck with access to black, but the thing is he costs one mana less, is a creature, it's easier to dispose of him if he threatens your life and most of all your mana curve in a competetive deck is slightly lower.

PS: Usually 3 cards per mill is enough, but you've got to keep creature count high(about 40%-50% of the deck) to net zombie on every trigger.

liqo I am aware of this Sidisi trigger only nets me 1 zombie per mill.

The idea to mill into a shuffler is so that Sidisi's trigger will reset off of that mill/trigger. It is irrelevant how many cards I dig deep for as long as I either hit Dread , Darksteel Colossus , Blightsteel Colossus, Ulamog, the Infinite Gyre and Worldspine Wurm to reset the Sidisi's Trigger and to not deck out.

So by activating Mirror-Mad Phantasm I will end up with several different opportunities to mill into the Mirror Mad even after shuffling increasing the chance of hitting the 5 creature shufflers or Gaea's Blessing netting me a zombie every time I reset the Sidisi's Trigger with each shuffle. Which could could net at minimum of 1 if I mill straight into the Mirror Mad. Ideally I would want to chain the shuffles to make net bonus zombies to attack with on my next turn. The process will take forever, and my friends probably won't like it but I think its worth trying out and seeing how it fairs in my meta.

This is pretty convoluted and lengthy but if this works ( I haven't tested this yet) it gives a new win con to the deck that I can do at anytime once I have the pieces and establish a board on my opponent's turn at instant speed without having to attack with my commander. It is completely stupid but its a personal preference of mine to have at least 1 stupid win con in the deck.

On a totally different note, I appreciate your suggestions in regards to Dark Tutelage and the self mill engine. Rhystic Study seems like a much better alternative. Hermit Druid is a card I never considered building the deck. He will fit right at home in current build.

I'm not sure if we understand each other. When you activate Mirror-Mad Phantasm's ability, the scenario follows:

1) during the resolution of the ability, you perform all the actions as instructed: "Mirror-Mad Phantasm's owner shuffles it into his or her library. If that player does, he or she reveals cards from the top of that library until a card named Mirror-Mad Phantasm is revealed. The player puts that card onto the battlefield and all other cards revealed this way into his or her graveyard."

2) while the ability is resolving all other actions using stack are postponed until the whole ability resolves/leaves stack

3) then any applicable abilities that were triggered by that ability are put onto stack (e.g. a creature entering battlefield, shuffling a library or a card being put into a graveyard from library)

4) let's assume now that before Mirror-Mad Phantasm you've revealed bunch of random creatures and Mr. Dread

5) since you've put all those revealed creatures into your graveyard at ONE TIME during resolution of Phantasm's ability, Sidisi's ability "Whenever one or more creature cards are put into your graveyard from your library, put a 2/2 black Zombie creature token onto the battlefield." will trigger ONCE

6) and because Mr. Dread was put into gy, his last ability will trigger

7) since you control both these abilities, you choose the order in which they resolve

Congratulations, you have Mirror-Mad Phantasm and one 2/2 zombie token in play, bunch of cards in gy and shuffled Dread for 1 mana! No infinite loops here.

If you want to play "I WIN" combos, there's plenty of infinite or semi-infinite combos with Sidisi, just ask a or search the internet =)

As for Darksteel Colossus and his infect bro, they have replacement effect "If Darksteel Colossus would be put into a graveyard from anywhere, reveal Darksteel Colossus and shuffle it into its owner's library INSTEAD." The scenario would be the same, except they are shuffled into library when Phantasm's ability instructs them to be put into gy. Also if milled, they don't trigger Sidisi's ability, because they technically never reach graveyard.