As far as R&D is concerned, it is the theme discard cards that cause the most unhappiness as discard decks are one of the scary three (land destruction, permission and discard) that tend to keep people from playing the game and thus tend to annoy players at a much higher level than other decks
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But actually, this isn't ideal for a couple of reasons Firstly, your opponents can crack their fetchlands in response to Hamlet's triggered ability, making it ineffective against any that are already on the field
In terms of other pricey cards that arent as notable, youre looking at Calculating Lich, Seasoned Dungeoneer, and Grim Hireling which all float around the $10 range
Sol Ring only survived due to it having special privileges, despite it falling under the exact same reasoning for Mana Crypt being banned
Usually in these sorts of game states you wont need to infinitely make your deck large enough, just for enough turns such that your opponent decks out before you reach a dangerous threshold