As far as efficiency goes, 3 damage for 1 mana is probably too much, considering Wizards of the Coast has kept it far away from Standard for a number of years
Forcing your opponents into combat can provide a significant advantage: it reduces the collective life totals at the table and temporarily immobilizes potential threats, creating the perfect moment to strike, which is why goad holds an edge over traditional removal in terms of interaction
Conveniently, Lillie's Clefairy EX does Psychic damage, solely via its two-Energy Full Moon Rondo
The bar of playability is much lower for a card that can work in a tribal deck (see: Cursecatcher in Modern and Mist-Cloak Herald in Standard), so the floor for Mistcaller is that it ends up a good option for Merfolk tribal decks
The fact that the First-Place Foil treatment, which includes the gold border, is mentioned for multiple other products in the Aetherdrift lineup lends credence to this assumption
With its energetic artwork and bright, swirling backdrop, Rotom V leaps off the card with a personality thats instantly endearing