Its a cool concept, but balance may be tricky. With SoP fractal, this thing could start gaining 20+ extra attack each turn.
I'm not too worried about SoP/Fractal. You have to first fractal it, and then wait a couple of turns for SoP. It will grow quickly but takes time to set up. I don't think it will be too fast. For balance I try to check for potentially too good combo-y cards but there are always some that I miss
How does Antimatter affect this?
The way I intended at first was that Emerging would not be dependent on the creature attacking at all but rather on the opponent's HP dropping when said creature attacks.
Since an AM'ed scorpion can't directly make the opponent's HP decrease, it doesn't deal "damage" and thus triggers Emerging. Poison is more of a universal/independent variable (if you kill a scorpion that gave you 10 counters, you'd still have those 10 counters), and isn't a creature, so it doesn't count for "damage."