That reflects the increased cost of UB products in paper Magic, and since the prize involves physical Magic cards, the entry fee goes up accordingly
Since then, the older client been rather overshadowed by Arena, whose ease of use and free to play economy has been very successful at bringing in new players
As milling has a mental attack flavor, it is very natural in blue
Chop Down can take down creatures with a power of four or greater
Prison/stax decks stop your opponent from playing cards and attacking you while gaining incremental advantages over time, be it with lifegain, Treasure tokens, or card draw
Such a thing would probably only prevent attacking or blocking but still, there is quite a lot of design scope to cover just in the realms of fair Pacifism like cards that cantrip