Basically, they make it so that both spells and abilities that your opponents control cost an extra two mana to cast or activate if they target a Merfolk you control
Later on, when you wish to cast three-drops with simple casting costs such as Tersa Lightshatter, you can simply tap Starting Town for colorless mana and tap a different Land for red so you dont have to pay life
Not only does it provide an untap just for attacking, it gives a +2/+2 buff, and Totem Armor, whichll save your fattie from a board wipe
Put the top two cards of your library into your graveyard
(Hilariously, cognitive dissonance will likely enable many players to ignore the drop in their collection value as they happily run out to scoop up cheaper staples.) From the speculators perspective, this paradigm shift towards accessibility suggests that holding Modern staples for more than a few years after release is going to be a very risky game