Itll shine brightest in token decks, but I could honestly see this being a solid include in any green deck with a lot of creatures
But your new best friend can copy your stuff over and over again, and works as many times as you have triggers that meet that condition
Then there is another deck this works in...see it
Neither of them broke the format, and most decklists are sticking to traditional and more reliable methods of counterspells
Part Birds of Paradise, part Scavenging Ooze, part Grim Lavamancer, the Shaman was banned in Modern and Legacy but never broke into Standard or Pioneer, although a critical mass of pseudo-fetchlands will eventually push it into playability
Additionally , competitive players appreciate the strategic versatility and high impact of these cards