The idea of him in my mind was someone who came and brought winter with him (representing the difficulty supporting large numbers of creatures) and then when enough time and seasons happened he became aware of what he was, and began his planeswalking
Along with his best chum Ashnod, he also takes great pleasure in sacrificing these creations for even more advantage from simple synergies
If the roll happened because of a replacement effect as part of a static ability (for example, the ability that sets Vedalken Squirrel-Whacker's base power and toughness), that ability isn't copied
You can easily include cards in your deck that combo directly with Unctus, like Tidewater Minion
I believe Wizards of the Coast have hit these preconstructed Commander decks out of the park
If protected by a character with Bodyguard, or simply used against someone who perhaps isn't paying enough attention, Bambi has the potential to quickly ramp up the lore