So far I've gotten two games in, and the deck was doing its thing in both. It's "thing" revolves around 'The Ring Tempts You', with the primary value being both milling an opponent and ramping a land from them. As such, I have some anti-graveyard tools, some punishers, and some landfall/land-centric cards.
To really get the deck humming, we want a sac outlet and fodder in order to trigger Smeagol each turn, and ideally want a way to do so multiple times per turn. Smeagol himself only really cares about 1 creature dying per turn, so anything that makes a body, or is easily recurred once is suitable. One of the strongest cards in the deck thus far has been his other half, Gollum, Patient Plotter. It needs some fodder of its own, but assuming some is available (the best being Scute Swarm), you can trigger Smeagol (and any other Tempt triggers) for every you can pay to cast Gollum, sac it to something, then activate it from the yard to sac something else and return it to hand. At minimum, this will get you a land and mill some cards from an opponent. Speaking of value...
Combos:
Sméagol, Helpful Guide + Gollum, Patient Plotter + Scute Swarm + Phyrexian Altar
Sméagol, Helpful Guide + Dúnedain Rangers + any landfall makes a creature + a free sac outlet
There are probably more. I don't want this to necessarily be a dedicated combo deck, but the first one above is going to help get you there even without being infinite.
The deck feels like it should be ramping at least one additional land basically every turn starting on turn 3 or 4, and can quickly get to making 2+ ramped lands/turn.
Bloodchief Ascension and Leyline of the Void are a nonbo, and I'm not sure whether I want to cut one, or just accept that they're both good here and sometimes I'll run into both together. Leyline helps cut players off from gaining value from my milling them, but would also preclude my getting additional value from milling them (like Rise). Notably, it doesn't stop me getting a land, since that's snatched from the reveal before everything goes to the yard.
Tenacious Underdog was surprisingly good in the first game, where I was able to keep running it into a blocker. Without a sac outlet or an opponent who is willing/foolish enough to block and kill it each turn, the blitz sac trigger will be too late for Smeagol's trigger.
Some stuff the deck needs:
Tireless Tracker - to provide a source of draw. In the first game, I ended up empty-handed for a few turns after some ridiculous removal. This would have helped.
More ways to get either Urborg, Tomb of Yawgmoth or another card to make optimal use out of the stolen lands (hitting off-color fetches sucks, and there's only so much generic mana to spend other off-color lands on).
Probably Rise of the Dark Realms. I've debated adding that to a few different decks, like Captain and [card="Henzie "Toolbox" Torre"]Henzie[/card], but felt like the former was struggling to get to that much mana at times, doesn't have haste, and has a hard time getting to 9+enough mana for interaction to stop the inevitable wipe afterward, while the latter doesn't do much to fill other yards other than a little removal, and also can't protect the scary board from a wipe. Smeagol, on the other hand, both fills yards, AND makes GOBS of mana.
Maybe more life gain. The Cavalier of Night and some food tokens I made off the Provisioner instead of treasure helped pay for life lost to Library and Call, as well as the combat hate I was getting for running away with things.
I don't have any land recursion to support The Gitrog Monster, which didn't matter much this game: basically, I swapped a land of mine for one of my opponent's each turn, then also added 0-2 of my own land drops, so I was still progressing.