Just a bit of sideboard input: I would cut the last tormod's crypt and add another grafdigger's cage. Grafdigger's cage sticks around to trigger metalcraft and hoses elves. Additionally, it's not a one shot use. I'm also not so sure about catyclism because it costs 4 and creature based decks make up a very small part of the metagame. In the mainboard it also seems like you can't reliably trigger metalcraft for mox opal, so maybe increasing your early game artifact count is the way to go.

Maybe ethersworn canotist in the main...

Aidenfoucault--Thanks for your input!

The reason that I like having a copy of Tormod's Crypt as opposed to the 3rd copy of Grafdigger's Cage is because Grafdigger's Cage can't actually remove the cards in your opponent's graveyard, while Tormod's Crypt can. I was debating using Relic of Progenitus to avoid the one-time use downside, but I decided on Tormod's Crypt because it costs 0 which helps with metalcraft.

Although creature-based decks may not be huge in legacy, I have a singe copy of Cataclysm because I need at least 1 piece of creature hate or else I would be killed by decks like goblins.

With all the artifact lands running around in the deck, it is actually relatively easy to activate metalcraft in the early game for Mox Opal.

Ethersworn Canonist definitely could go in the main, however in some matches it would just be a vanilla 2/2. Also, what would it replace?

Thanks again for your suggestions!

Elbrus, the Binding Blade  ^Flip

Ethersworn Canonist

Colgate--Although Elbrus, the Binding Blade  ^Flip is good, it is too situational to warrant a spot in this deck (you need to play it with Stoneforge Mystic, the creature needs to deal combat damage, etc).

matthew352--Ethersworn Canonist is already in my sideboard...

Argentum Armor is even more situational, you need to play it with Stoneforge Mystic and equip it with Puresteel Paladin,

But Argentum Armor has a much bigger reward when you equip it, whereas you still need to deal combat damage in order to transform Elbrus, the Binding Blade  ^Flip. Also, the demon can easily be removed.

I dont think you should run either Argentum Armor or Elbrus, the Binding Blade  ^Flip. Both are too situational. Don't be fooled by how good the effect of Argentum Armor is, you need 2 of your creatures to be able to play and equip it. This makes it a 3 card combo, that is easily disrupted with a single Lightning Bolt or Swords to Plowshares.

Ok, so what should I run instead?