Blue is my favorite color to play in Magic, and even though creatures arent usually at the forefront of blue decks, it still has some of the most powerful creatures in the game
Im pretty sure they mean planes walkers, but what are Magic players if not pedantic
At the end of the day, is there really anything worse than watching your opponent play your own cards against you
You want cards that work as mass artifact destruction as cheaply as possible, so Farewell usually wont do it at 6 mana
Its obviously a much less powerful card overall, and you cant just throw it into a deck with no concern for what else is in there, but its possible there is a deck built with The Cauldron of Eternity in mind and then this deck could want Gray Merchant, but it really has to be a dedicated self-mill deck for it to work, because if you cast Gray Merchant and it dies naturally (which is the most common play pattern), it doesnt work with the Cauldron unless the Cauldron isnt on the battlefield yet