Sure, he works in other decks, but Elves is one of the decks that leverages all three of his abilities
Beyond Merfolk tribal, the downside of Mistcaller is that it's just a 1/1, meaning it doesn't present a very fast clock and dies to Goblin Chainwhirler, which probably keeps it out of main decks in both Standard and Modern
The Core Constructed main event is capped at 2,300 players
I like this commander a lot, which will be a surprise to nobody, knowing 80% of my currently assembled EDH decks are in Dimir colors and the ones that arent are Esper and Grixis colored
While Belle may be a little underwhelming (moving damage around hasnt been a viable strategy yet), Amethyst does boast what just might be the most powerful draw engine in Amethysts toolbox: Second Star to the Right
Then its easy to see if, after including all the cards we want, where our big gaps lie