That's not even limited to bears, the power scaling for MtG cards in general is logarithmic. The most famous example being the fact that Emrakul, the plane-eating eldrich god and most powerful card ever printed, can be defeated by 15 1/1 squirrels.
I think this card could work with something like "Whenever Eight Fucking Bears is dealt damage, place that many -1/-1 counters on it." Maybe make it cost 2F instead of 1F.