Introduction I've been trying to make a Kaldra deck for as long as I can remember, long before EDH was a thing. I've tried various themes, color combinations, and commanders, but none of them ever felt very satisfying. When Stoneforge Mystic was printed in original Zendikar, the equipment specific tutoring was very exciting. When Purphoros, God of the Forge was printed, it was now possible for Kaldra to attack from a different angle. Over the past few years, WotC kept on printing incredible Boros card after incredible Boros card, and all that was really missing was the perfect commander. Enter Archangel Avacyn. It's been a long journey, filled with heartbreak and regret, but I am convinced they are a match made in heaven.
Archangel Avacyn and Shield of Kaldra give your permanents indestructible (in their own way). When Avacyn & Kaldra are the focus of the deck, it's easy to make indestructible a sub-theme of the deck.
The exile effect from Sword of Kaldra equipped on Avacyn can completely and permanently wreck everything on the board. (Yes, this has some anti-synergy with indestructible, but desperate times and all that.)
Once Kaldra is assembled, with you can create a Kaldra token and with another you can legend rule them both to the graveyard -- triggering Avacyn to transform on command.
Flying & vigilance are 2 of the abilities not granted by the Kaldra artifacts; a loose distinction, but important for voltron considerations. A 9/9 flying, first strike, trample, haste, vigilance, indestructible creature that exiles anybody that it touches (and exiles everyone else when it dies) will get your opponent to 21 commander damage real quick.
The first version of this deck packed as many Boros infinite combos into the deck as possible -- there are many. And the deck only used the Kaldra set as a back-up, sometimes non-infinite combo piece. The way it works is because Kaldra can be used to summon additional legendary Kaldra tokens for :1mana:, this means it's very easy to make infinite mana with things like Ashnod's Altar or Phyrexian Altar. This also means that you can trigger infinite "enters the battlefield and "leaves the battlefield" triggers to combo with things like Purphoros. That deck got boring real quick and "going off" became the focus of the deck and "Kaldra" was just an afterthought back-up when things go wrong. (It stopped being a "Kaldra Deck.")
Putting that version of the deck aside, with this, you can still "go off" with Purphoros, dealing 2 damage to each player for each you spend. If you ever have Kaldra assembled with Purphoros on board, your opponents still have to deal with it immediately, but there is a window where they have a chance.
Deciding not to include any infinite combos, I was forced to not include a few cards which would be perfect, like Boros Reckoner (gaining infinite life). It's very easy to go infinite with Boros and sacrifices has to be made. On the other hand, this forced me to include other non-infinite options. For example, Avacyn is at its best when you're able to sacrifice a creature on command. This is the reason why non-infinite sac options are in the list such as High Market and Greater Gargadon.
Why shouldn't you play this deck?
Boros Things - This deck feels unique enough to me when I play it, and yet it still includes Boros things like Aurelia, Iroas, and Gisela. If you're sick of those cards in any form, this deck isn't for you.
Heavy Tutoring - When this deck is built around finding 3 specific cards, it's inevitable that it will include a heavy amount of tutoring. And when you consider that some of the tutoring cards are creature based, every recursion effect is yet another potential tutor effect.
Ashnod's Altar - Same infinite loops as Goblin Bombardment, except also creates infinite mana.
Goblin Bombardment - Same infinite loops as Phyrexian Altar, except also deals infinite damage while looping.
Boros Reckoner - Unfortunately, it's very easy to gain infinite like once the reckoner gets both indestructible + lifelink.
More info to come. I will update later. With individual card breakdowns and also a list of cards that were considered, but didn't make the cut for one reason or another. Also, this list isn't fully complete. The nonland cards listed is still in the 50's. Looking for some suggestions. Just remember, I want to avoid infinite combos as all costs and stay away from "Boros good stuff" for the sake of including good stuff.
Figure of DestinyOUT --> Kytheon, Hero of AkrosIN - This is mostly due to Figure of Destiny underperforming. This deck creates a lot of colorless mana and it just becomes awkward to power up the Figure. But when searching for a replacement, I think Kytheon has slotting in nicely. This deck doesn't really swarm your opponent, but his flipped side does a lot of what this deck wants to do. I'll try him out for now. I'm usually against Double-Faced Cards. But if I'm going to use them, might as well see how far I can take it.
Thran DynamoOUT --> Honor-Worn ShakuIN - Comes down a turn earlier, higher upside, lower base power, and much less consistent. Honestly, it's just kind of fun to use the Kaldra artifacts to generate mana. EDH doesn't have to be so serious. I've also decided to limit the number of mana rocks to 10 for this deck. Also, with Kaldra + Purphoros, every other legendary Kaldra token can be used to generate :1mana:, effectively increasing the amount of damage you can deal each turn by 50%.
Weathered Wayfarer, Oreskos Explorer, and Knight of the White OrchidIN - Many great suggestions, going all in on this "Land Tax" theme (which works well with Greater Gargadon). This also makes it very easy to limit this deck to 4 basic mountains. I feel like this is the correct number. When you add up all other mana sources and tutors, this deck effectively still has close to 20 red mana sources. And maximizing basic Plains feels important for Emeria.
Many changes over the past week. Here are the highlights:
Stonehewer Giant & Quest for the Holy RelicIN - I was fighting the giant for a long time, mostly because it wasn't a human or angel (Bruna) and it didn't have a power of 2 or less (Reveillark, Imperial Recruiter), it wasn't legendary (Loyal Retainers), or an enchantment/artifact (Enlightened Tutor). None of my situational recursion or tutors can target it. But with a little testing, the instant equip from both Stonehewer and the quest are just great with Avacyn. Too good to pass up.
Karn, Silver GolemIN - Shield & Sword of Kaldra have high equip costs. Much like Honor-Worn Shaku, Karn gives them just a little more utility. And if this is a Kaldra deck, I might as well go all-in. Karn is also nice with Smuggler's Copter -- animating it instead of crewing it -- while still getting the looting effect. (I tried to force Skysovereign into the deck, but with Reveillark & Imperial Recruiter, the majority of creatures that would want to crew it have a power of 2 or less. I consistently needing 2+ creatures to crew it make it very un-weildy.
True ConvictionOUT --> Darksteel ForgeIN - Other than combo'ing with Avacyn, True Conviction was just a win-more card in almost all cases. Darksteel Forge somewhat combos with Avacyn, but also with Oblivion Stone/Nevinyrral's Disk. It's another great target for Goblin Welder. And it's a huge artifact for Karn to play with.
Inferno TitanIN - This deck felt like it needed just a little more redundancy for abusing Sword of Kaldra & Basilisk Collar.
Mishra's WorkshopIN - There is a decent amount of artifacts in the deck, but it's not completely stacked. But this deck is a little bit of a glass cannon when it comes to assembling Kaldra.Like many things in this deck, if I'm going to go for it, I might as well go all-in.
Lotus Vale & Scorched RuinsIN - Lots of taxing effects. Decided to go high risk, high reward. Some blow outs, having fun so far. And even when you're punished, this deck can recover. Mox Diamond is also very good here, allowing you to dump these lands when needed.
Waves of AggressionIN - Kind of fills the space of True Conviction for those blow out, combat wins. Plus, it's not vulnerable to my sweepers and it has synergy with land. Seems like a good fit.
Those are the major changes for now.
The deck is still very weak to opposing enchantments & artifacts. Oblivion Stone, Nevinyrral's Disk, Druegar Hedge-Mage, and Wear/Tear are basically it. (Although this deck has the potential to use the first 3 over and over and over through the course of a game.)
Skullclamp is currently next in my sights to cut, but it just might be too good, even without abuse. Other than Hanweir Garrison, this deck doesn't really produce tokens. Still, this deck has lots of creatures that fetch other creatures. And you really only need the clamp to go off twice before you feel like it's unfair.
edit: I still have not updated the main text of the OP, so it will not exactly reflect the current desk list.