But a decade later, Wizards would print Protean Hulk, which turned Flash into a Turn 1 win thanks to a convoluted loop of creatures that you can tutor up by using Flash to not just cheat the Protean Hulk into play but immediately sacrifice it, which was oddly an upside due to Protean Hulk's death trigger
Again, it depends on your environment how deep you go with sideboard cards
On paper, it seems pretty balanced and self-restricting, for sure there won't be any oppressive card with this ability
Marchesa, the Black Rose : When I build Marchesa decks, I use plenty of creatures that naturally enter the battlefield with +1/+1 counters, which means that, with Marchesa, the Black Rose on the battlefield, we can feed one to emerge without going down a card