Ricardo Silva Ive written an article about Mishras Baubles prevalence and utility in Modern for Three For One Trading in the past
Each dungeon will stay flipped, letting you compare the dungeons if you aren't a veteran adventurer yet
A land that replaces itself with a card can be effective in the late game to mitigate flood and find that last card you need, but taking damage every time you tap for mana adds up quickly
Yes, that is also the main disadvantage to getting card advantage through drawing cards and yes, discard is also weakened by diminishing returns which card draw isn't, I am not comparing discard to card draw as a way towards card advantage, just stating the facts about cards in isolation
Even better is that it attacks for free, meaning it can be thrown into any deck out there
His basic stats would be just about playable in a modern draft as a game ender, as he's a seven / seven with flying and trample that costs seven mana