Oswald supports putting together lots of value and using Mechtitan Core to create a big and fast creature that can swing games.
First off, we need to start accruing value. A good Oswald line for this is: 0-Drop -> Implement of Improvement -> Ichor Wellspring -> Circuit Mender/Filigree Familiar -> Solemn Simulacrum -> Precursor Golem.
What this line does is, over the course of 5 turns, Draw 5 + Three 3/3's. This only costs 1 mana per turn which allows you to hold up mana for interaction (like Mana Tithe or Dispatch), or play artifacts with useful static abilities (like Foundry Inspector or Esper Sentinel).
Next, we need to start improving Oswald's ability. If Rings of Brighthearth, Thousand-Year Elixir, or Mirrorworks haven't been drawn yet, it's important to tutor those up quickly. A line for that might look like: 0-Drop or Token -> Arcum's Astrolabe -> Myr Sire -> Rings of Brighthearth/Thousand-Year Elixir.
Both of these 3-Drop artifacts make Oswald especially effective at tutoring artifacts out of the deck. Rings give you double the value out of a single artifact, and Elixir allows you to jump up two Mana Value in a single turn instead of just one Mana Value (meaning you can get from a 3-Drop to a 5-Drop).
After upgrading Oswald's ability, it's time to start some recursion since we are running out of low Mana Value artifacts. To do this, we need to bring out Junk Diver, Scrap Trawler, and Sanctum Gargoyle. If we've drawn Teshar, Ancestor's Apostle by this point, we are definitely in business. These four cards make up the backbone of our artifact recursion. We've also got emergency recursion in our sorceries (Sevinne's Reclamation/Refurbish/Open the Vaults/Brilliant Restoration) in case our recursion permanents all get taken out. We even have Pull from Eternity as a last-ditch attempt to save important pieces that have been exiled (as well as synergizing with the true superstar of this deck).
Now for the pièce de résistance. Mechtitan Core is the whole reason we are piloting this deck. It's a fun and silly reference to Super Sentai (or Power Rangers in the West) that has a very interesting mechanic to play around with. By itself, the Core can quickly summon a Legendary 10/10 Flying, Vigilance, Trample, Lifelink, Haste token that can do some serious damage. The downside is that the Core exiles itself and does not return with the rest of the squad after the Mechtitan is defeated.
In order to combat this one-trick-wonder ability, we have a few interesting tools in our toolbox. Mirrorworks is a great way to get token copies of the Core in order to use THEIR ability to summon Mechtitan instead of the original Core. A cool piece of tech to use here is to use the original Mechtitan Core as one of the artifacts exiled using the Core Token's ability. This means once that Mechtitan is removed, the original Core returns to the battlefield and can be cloned by Mirrorworks AGAIN. It's a great way to get a lot of mileage out of the Core.
Another cool piece of tech is copying Mechtitan Core's ability using Rings of Brighthearth. This will create two Legendary Mechtitan Tokens and if either are removed, all of the components exiled to summon it will return. Well, thanks to the legend rule, that will happen IMMEDIATELY. Meaning you get the Mechtitan + all of the components on the battlefield at the same time. You can even combine this with the Mirrorworks tech above to continually pump out powerful 10/10 tokens while also getting lots of ETB triggers from your components re-entering the battlefield (Altar of the Brood anyone?).
Mirror Box and Anointed Procession can be used to start churning out Mechtitans to just beat our opponents down. We can also slap on a cheeky Grafted Exoskeleton to quickly end a troublesome opponent. One last interesting bit of info is the fact that our Mechtitan Token counts as being every color which is why we are running Conqueror's Flail to beef up the Mechtitan even more (or throw it on Plague Myr to make our opponents sweat). Chromatic Orrery turns into a pay 5 to draw 5 whenever Mechtitan is out. Lastly, Happily Ever After is super cute and will probably never win us the game, but it would certainly be funny to suddenly win the game whenever we pop out a 5-colored Mechtitan at instant speed just before our turn (yeah Mechtitan Core can activate it's ability at instant speed).
All-in-All this is a silly deck that can still churn out value and summon big dumb mechs to beat in our opponents' faces. Hope you enjoyed reading!
