Also, that makes it an additional cost, not an alternative casting cost (in fact it states such explicitly right on the card), so Shared Discovery doesn't actually cost just one , it costs more , in the form of needing creatures already in play
It just sits on the battlefield growing absolutely everything, and if your opponent can't deal with it in a turn or two, they'll have already lost
There are pros and cons to each, but Incineroar Ex remains the star of the show thanks to its Burn damage and ability to deal massive damage in a single hit
Kaladesh, like most artifact sets before it, was pushed to the limit as far as power level was concerned, which led to multiple bannings in Standard (and was around the start of bannings being so in vogue in Standard)