Blood Moon and magus of the moon are broken. It is a red enchantment that only costs 2+r and turn all nonbasic lands into mountains. Not in addition, instead. Harbinger of the sea is the same but 2+blue and islands instead of mountains.
Pretty OP to be able to force opponents lands to only produce red mana. It should either cost at least 5-6 mana as 3+rr or 4+rr. Or it needs a stipulation, like cumulative upkeep, discard a card or sacrifice a permanent at upkeep or sacrifice the enchantment, pay x life, destroy if you control no (card type), or even just let it have "are mountains in addition to their other types" like how stormside leviathan, swampbenders, yavimaya cradle of growth, and Urborg tomb of yawgmoth - all of which change all lands to a basic land type in additon. Being able to deny someone access the the mana ALL non basiclands produce AND remove ALL of those lands activated abilities is just excessive.