Steel Overseer is a creature that's powerful enough to show up in Modern but has been in Standard for several months now without making any impact. Throne of Eldraine gives us Emry, Lurker of the Loch and Stonecoil Serpent, which could be enough to warrant playing an artifact-based aggressive strategy.
Emry, Lurker of the Loch is going to be powerful in quite a number of decks, but in a deck built around artifacts it's basically going to draw you an extra copy of the best card in your deck every turn. Steel Overseer encourages us to play a lot of small artifact creatures, so let's see what we can do.
Corridor Monitor happens to interact nicely with both of our aforementioned all-stars. It has a body that sizes well when being buffed by Steel Overseer, and its untap trigger provides an additional activation. With Emry this card is even more fun, since you are able to recast any number of copies that are in your graveyard that you have mana for, and end the chain by untapping Emry yet again to cast another artifact.
After establishing this shell, there are a few ways that we could go about constructing this deck. Let's first examine a straightforward aggressive version of this deck.
Artifact Aggro with Throne of Eldraine
4 Emry, Lurker of the Loch 4 Steel Overseer 4 Stonecoil Serpent 4 Chamber Sentry 4 Corridor Monitor 4 Gingerbrute 4 Arcanist's Owl 4 Clockwork Servant 1 Crashing Drawbridge 4 Mystic Forge 4 Watery Grave 4 Steam Vents 4 Hallowed Fountain 4 Breeding Pool 7 Island (335)
Stonecoil Serpent has a ton of keywords that make it pack a bigger punch than an already flexible vanilla X/X for X would be. Chamber Sentry is a little less powerful, but still flexible and its ability to shoot down small creatures can be useful against something such as the Cavalcade of Calamity deck that is sure to be running rampant in the new format. Even if we end up running a mono blue list, we can include a smattering of random shocklands to be able to cast it for more than 1 (and even potentially live the dream of rebuying it from the graveyard).
Gingerbrute is not the most impressive turn 1 play in the world, but we don't have a ton of options for artifact creatures at the 1 slot. However, it does utilize the +1/+1 counters from Steel Overseer quite well, with an evasion ability that is basically the same as unblockable against most decks.
The other key payoff for a deck like this is that we're playing a lot of actual artifacts such that Mystic Forge does a very good Experimental Frenzy impression while also filtering your draws and letting you cast cards from your hand.
Arcanist's Owl and Clockwork Servant are some solid value creatures that let us keep chaining more artifact creatures into play. They do a good job helping us dig for Steel Overseer or Mystic Forge, but they also encourage us to avoid playing colorless mana sources such as Renowned Weaponsmith, Mobilized District, or Karn's Bastion. We're already encouraged to do this for Chamber Sentry, so this actually slightly strengthens our manabase.
Crashing Drawbridge and Shambling Suit are a couple more options for artifact creatures to include, though they are on the weaker end. We've opted for 1 copy of Crashing Drawbridge in this list, since it provides the most unique effect. It can guarantee that we get value off of a Steel Overseer or Emry, and it can provide a late-game threat if we ever pull off a big Mystic Forge turn or cast a huge Stonecoil Serpent.
But what about the powerful planeswalkers that can produce artifact creatures? While it is sad that Karn, Scion of Urza has rotated, we can still use Saheeli, Sublime Artificer and Dovin, Grand Arbiter. We can reshape the deck entirely to take advantage of these powerful 3-drops.
Azorius Artifact Aggro
4 Emry, Lurker of the Loch 4 Steel Overseer 4 Stonecoil Serpent 4 Corridor Monitor 4 Saheeli, Sublime Artificer 4 Dovin, Grand Arbiter 4 Opt 4 Glass Casket 4 Unsummon 4 Hallowed Fountain 10 Island (335) 8 Plains (331) 1 Karn's Bastion 1 Mobilized District
Glass Casket and Unsummon are included in this version because we need to include enough noncreature spells to support Saheeli. These cards give us some quality interaction that the previous linear strategy is lacking, allowing us to get through for damage or protect our planeswalkers. Glass Casket is a sweet card to mill with Emry, and Unsummon can get tricky by either protecting one of the key creatures, getting another mill from Emry, or even bouncing Corridor Monitor to get an extra tap activation right away.
The manabase for even a 2-color allied deck is ugly in the current format. We could include Fabled Passage, but a lot of our key plays involve using all of our mana on the second and third turns. Since our color requirements are relatively light outside of Saheeli, it looks like we can squeeze in *just* enough colored sources to get by and still include 1-2 copies of Karn's Bastion or Mobilized District. Karn's Bastion does a good impression of Gavony Township with a Steel Overseer in play, and Mobilized District does a good job at helping to protect our planeswalkers.
Tezzeret, Master of the Bridge is another possible way to go with this type of deck, but it's a bit harder to build. We need to find a way to include some mana ramp that lets us actually cast the 6-mana planeswalker, such as Midnight Clock or Mana Geode. While extra mana does pair nicely with Stonecoil Serpent, it takes away from the Steel Overseer focus. Perhaps we could brew some weird list that includes Jiang Yanggu, Wildcrafter and abuses the proliferate mechanic more with all of these creatures that naturally create +1/+1 counters. Whichever way we go, you can be sure that Emry will be great in it!