when it was announced, collectors debated about its worth and how to assign value to it in the first place
With a Blue mana cost, Kelpie Guide is castable in a Prismari deck, but the flavour text makes it clear this flighty beast favours Quandrix mages
Godo and Helm might be an easy include as well, since helm and your commander win in a few turns, with the math meaning if you have both your commander from the start of the turn before attaching helm, and have no other goblins, you activate them both after making the new one and get a total of 8 on the first turn, 72 on the following turn, and 1168 goblins on the turn after that, most likely winning the game
When the last is removed, you may cast it without paying its mana cost
The first drops for two, gives you an 0/5 Wall, and you can put -0/-1 counters on it to make mana