Cards in general from Alpha, Beta, and Unlimited found in grading-worthy condition are already exceedingly rare, so a copy of Magics most iconic card, from its first set that is in perfect condition is where the the hefty price-tag comes from.
Clans, in order: 1
Elvish Reclaimer builds can technically fetch up Bog as early as turn two, but that line costs you a land and your entire turn, which is a steep price to pay against decks that are trying to kill you immediately
Nicol Bolas, the Ravager / Nicol Bolas, the Arisen I loved playing with Nicol Bolas, the Ravager while it was in Standard and still enjoy tinkering around with it in Brawl and Commander
With high production quality and carefully designed mechanics, it has gained traction among serious TCG players and tournament organizers
Technically, the "first rookie" title is a split between distribution and set chronology: while the Luffy PR001 (Pirate's Ambition) was the very first card to reach the public via the October 2005 issue of Shonen Jump (hitting newsstands in mid-September), the CH001 is universally recognized as the true "Origin" card of the game