They're one of the original 'tribal' creature types: fish folk has been a viable strategy since the very earliest days of Magic: The Gathering
Overall, this is a card that can give you a lot of tempo as well as function as spot removal, so it has some flexibility
Im not wild about introducing more partners into the mix, but this legendary Dog seems like theyll be good
One black Wizard pinging opponents for every cast spell is going to annoy the table, but if you can amass a few of them, you'll become a problem
But people play it a lot, and its well-liked by everyone who does
So it takes some work and protection spells, but wouldn't you say continuous Elspeth Conquers Death chapter 1s, or Jugan Defends the Temple chapter 2s are worth it, plus the more sagas you tick back, the stronger Garnet gets