Wizards of the Coast has said that proxy cards are not allowed in competitive play such as sanctioned tournaments
Ideally, you can start out early with cards like Siren Stormtamer and Fathom Fleet Captain, then cast your commander on the same turn you plan on fulfilling her end step trigger
The Shepherd allows us to destroy artifacts and enchantments as long as we have a total of four creatures
It scales up with your mana as you go later and later into the game from a nice midgame removal spell on one dork to a decent two removal dork for six mana a few turns later to three or four in late game, and getting that many removal spells on one card is incredibly strong
Suffice to say, decks play these lands without downside most of the time, and they shine in 1- or 2-color decks
Its not quite Mind Rot, but it gets either two lands or a spell, which is a bit better than your opponent discarding an excess land