I mean, Izzet Pirates are still dominant, but we have witnessed other interesting specimens that could provide a more varied take on this classic tribe in Standard
Like most Magic: The Gathering cards, the value of Gogo, Master of Mimicry depends on a few consistent factors: its rarity, the printing and finish (regular or foil), its physical condition, and the set it was printed in (Final Fantasy)
Those were (and are) at the top of the metagame, and the concern was that their stifling effect on the rest of the metagame would grow and we'd see the Standard metagame becomes less diverse over time
This is so effective because your opponent cant target the hexproof creatures themselves, which means you can safely put as mana auras on them as you want
With Saheeli, Radiant Creator you pay three energy to put a creature from the top four cards of your library onto the battlefield and deal 2 damage