One way to stop a landfall ability is to make sure that the ability has no targets
Because it can get Plains, it won't fetch basics for getting mana, but it can get multicolored lands that are Plains, such as Plateau or Hallowed Fountain

Disney Lorcana: The First Chapter Full Card List Abu Mischievous Monkey Aladdin Cornered Swordsman Aladdin Heroic Outlaw Aladdin Prince Ali Aladdin Street Rat Aladdin Heroic Outlaw (SR) Anna Heir To Arendelle Archimedes Highly Educated Owl Ariel On Human Legs Ariel Whoseit Collector Ariel Spectacular Singer Aurora Briar Rose Aurora Dreaming Guardian Aurora Regal Princess Aurora Dreaming Guardian (SR) A Whole New World Be Our Guest Beast Wolfsbane Beast Hardheaded Beasts Mirror Befuddle Belle Inventive Engineer Belle Strange But Special Belle Strange But Special (SR) Break Captain Colonels Lieutenant Captain Hook Thinking A Happy Thought Captain Hook Forceful Duelist Captain Hook Captain of the Jolly Roger Captain Hook Ruthless Pirate Cerberus Three-Headed Dog Chief Tui Respected Leader Cheshire Cat Not All There Cinderella Gentle & Kind Coconut Basket Control Your Temper

With a few counterspells or some way to give it hexproof, you can start dealing Commander damage with your opponents commanders
My Verdict: Whispersilk Cloak is a fantastic way to ensure your monsters get their hits in but be wary of the high mana commitment
Every time Raph & Leo attack, they untap one or two attackers and trigger an additional combat phase if this is the first combat phase of the turn