In response to several people's comments:
I edited the article and mentioned a few of the other cards that work well with the combo, however I didn't add too many. The beautiful thing about this combo is that unlike most others it's completely self reliant: it doesn't need any outside help to make it work. So any other cards you pick up delays getting a necessary component by a turn.
Also, I'm skeptical that any cards costing more than $3 will realistically be helpful. As you start picking up all those hermits it becomes increasingly unlikely that you'll ever have more than $3 to spend- at least not until you're ready to pull the trigger.
That being said, I'm surprised nobody has mentioned Band of Misfits: in a pinch they could be used as substitute Hermits or Market Squares if either is in short supply. Although I suppose that wouldn't work if either pile emptied out...
The combo is rock solid if the Hermits are uncontested, but I haven't seen any games with contested Hermits out here. And Hermit/Madman is a
very contestable card.
Let's say you split the Hermits 4/6, because hey that's what WILL most likely happen if Hermits are the most contested card and you go second. That gives you 4 Madmen. Okay play 2 of those to draw up to 14 cards in hand, you have 7 coppers from your start and let's spot you 4 Market squares, two trashers and an estate to trash. This means you can gain 4 gold by trashing a card, this however reduces your hand by 6 cards (4 Mrksqr, 1 Trasher, 1 Trashed card), playing a Madman will only draw you 7 cards (you had 8 in your discard). Trashing a Mrksqr will most likely get you 3 more golds and drop you down to 9 cards. You now have 9 cards in discard and draw 8 with your last Madman. You draw the rest with your Mrksqr's and so you end up with 6-7 gold or ~28 coin. Now that's a nice solid 3 provinces and maybe a duchy ... but that isn't game winning ... even buying a province next turn won't seal it for you - Madman is too good an enabling megaturns (Bridge, Horn of plenty, Highway, Governor, Coppersmith, Bank, Beggar, Vault/Secret chamber/Storeroom, Goons, etc.) which is likely what contested
Now let's be sneaky and add two cards to the above: a Coppersmith and a haven. With the haven you start with 6 cards, you gain get to 18 cards (9 copper, two trashers, 4 Mrksqr, Coppersmith, and two estates to trash) with two Madmen played. You trash a card and discard 4 Mrksqr, dropping to 12 cards in hand and having 8 cards in discard. You play a Madman, drawing all your cards, trash your other estate and draw all your cards. You play the Csmith. That gives you 8 gold and effectively 9 silver for 42 coin, enough for 5 provinces or 4 provinces and 2 duchies.
Yeah you'd do better with a 5th Mrksqr over the Csmith here, but I'd trying to keep parity here. You also can do much better with a second Csmith.
Likewise, as you've noted discard attacks hurt viciously and about 1/3rd of Madman/Mrksqr games will have a discard attack. A decent percentage of games will have no other trashers so even in a 6/4 split you will have to make do with only 4 Madmen draws. Then of course there are colony boards in contested Madmen games. There just are a LOT of times where you won't be able to get enough Hermits to build the full combo and lockdown the game. Enter all the other cards mentioned. Haven gives you MASSIVELY more flexibility and it is not like with all the Hermits/Madman/junk to trash in your deck you won't hit a few 2 coin hands and waiting for 6 or 7 card starting hand can be worth it. Tac can massively drop your needed Madman count or increase your payout, or let you play the combo even when being Militia'd every turn.
Yeah if the other guy doesn't go for Madmen, then buy very little costing more than 2 outside the combo. If he does, then you need to offer some strategy in your article other than "well you mostly likely lose if you go second and the other guy isn't ignorant".
Twoos: 2 Cash will often be very important for hitting 3 coin when your have colliding Hermit/Rogue & dead Madmen you do not yet want to play. With no additional treasure in deck, you have to hit 3 coin from 4 cards using only coppers with Graverobber, Rogue just needs 1 in 4 cards to be a copper. So Graverobber gains you a Hermit to deck top, Rogue let's gain a Hermit and more likely buy one as well. Lastly, near the megaturn you actually don't want the Hermit on deck top, you want more odds for Madmen so you can go off sooner. Graverobber does have the bonus of being able to trash actions ... but so does Hermit and the point of either trash diving card is to have plenty of Hermits when you fire off the megaturn.