(They each put the top card of their library into their graveyard.) : Each player mills a card
Poking around a bit, I found quite a few graded cards posted on eBay, and while sellers were asking higher-than-average prices for those cards, one thing seemed pretty obvious: The newer a Magic card is, the less likely grading it will have a significant effect on its value
You can make a free Map token with Worldwalker Helm when you make an artifact token and you can tap it to copy an artifact token you control, just like the Oltec
A 4/2 Dragon Shaman with flying for five mana, whenever you cast an adventure, or more importantly, whenever you cast a Dragon, you can deal damage equal to that spell's mana value to any target
The answer here is that in decks that are three or more colors, MDFCs have an additional drawback: they only add a single color of mana