New Creatures/Enemies for Existing Biomes that Only Spawn in the Deeper Reaches of World Seeds

Many know that the frequency of starred enemies has a chance to increase the further out one goes into the world.

But what about new creatures in existing biomes? At its furthest reaches, why shouldn't the Black Forest be more dangerous than it is near the center of a world seed? Perhaps giant ents akin to the Elder could be a rare, challenging spawn to fight. Perhaps moose/elk roam in the Meadows and Black Forest as well. Moose/elk could provide a new class of meat and hide for later-game content.

Or giant, hungry bears in the Meadows and Black Forest could spawn during night only, just as Wraiths do in the Swamp.

Furthermore, let's imagine the Swamp could spawn rotting skeletal counterparts of Trolls and wolves, whose corpses tumbled long ago into the mud and muck of the swamps to decay and respawn as a vile reincarnation of itself.

Perhaps the Plains could host Fulings which are much more viciously radical with their worshipping toward their king and thus are that much more dangerous than their standard fellows.

Edit: and of course, the mountains could properly host larger dragons compared to the common drake who could drop some juicy details.

My detailed suggestions, what does everyone think of the base idea?