Put Kor Firewalker in the deck. It will be ridonkulous.

There are a lot of soldiers out there, but some of the must-haves I feel you're missing are Brimaz, King of Oreskos , Preeminent Captain , Evangel of Heliod , Nomads' Assembly , Launch the Fleet , and Deploy to the Front . High Sentinels of Arashin and Elite Scaleguard could also be very powerful, depending on how much +1/+1 counter stuff you plan on doing.

If you're going to play the Earthquake deck, you might as well play Truefire Captain , Spitemare , and Boros Reckoner .

I think the deck could also use some more "vegetables" cards. You should be running Boros Signet , at minimum, but Boros Keyrune , Boros Locket , Mind Stone , Sword of the Animist , and Knight of the White Orchid should probably be in the conversation, as well. Vandalblast , Aura of Silence , Crush Contraband , Return to Dust , etc. are all removal you might consider over the abundance of creature removal you have. In terms of card draw, being tribal, you could look into Vanquisher's Banner could also do work.

As for cuts, you shouldn't be running Evolving Wilds and Terramorphic Expanse in a 2-color deck. Ancient Amphitheater , Needle Spires , and even Stone Quarry are all strictly better without cards that care about land types or Landfall. The deck thinning is inconsequential in a 99-card deck, and you'd rather have the flexibility. Catapult Master, Hour of Devastation (you know it removes indestructible, right?), Deafening Clarion, and Hammerfist Giant all seem pretty suspect to me, just on card quality. Rather than Deafening Clarion, Firesong and Sunspeaker seem better with the Earthquake theme.

I was just looking at Preeminent Captain earlier today, and thinking he would be great for this deck. Other useful generators are Brimaz, Nomads' Assembly, and Deploy to the Front.

Before I started using the deck, I considered adding Truefire Captain and Spitemare, but wasn't sure how often they would come up with Tajic on the field. Now that it has seen use, I think they could be instrumental in redirecting lethal damage when I don't have mana to get Tajic back on the field, but can play one of them and Blasphemous Act. Also good for punishing someone who removes Tajic in response to one of my Earthquakes.

Meh. I don't think the rocks will do this deck much good. There is so much low-drop value in the deck already, I would rather drop Soldiers Turn 2-5 to support Tajic and start beating face early than slow myself down with rocks. The artifact/enchantment removal you mention, though, does seem fairly useful. I can think of a couple times in his games so far when those have been a problem. Single-target removal would need to be hard exile like Crush Contraband, too much recursion in my playgroups otherwise. Also, Vanquisher's Banner seems like it could go a long way towards helping my spells replace themselves.

I see what you mean about Wilds/Expanse. Will cut those for the others once I make the acquisitions. Catapult Master is beautiful for the targeted exile, it has already won me a game. You're right, Hour of Devastation does remove indestructible! I only have 1 source of that in the whole deck, everything else is regenerate or prevent the damage. It doesn't hurt me, but lets me take Gods off the field. Just did that to a Heliod in my last game (it blocked a Soldier token, died to Devastation main phase 2). Hammerfist Giant is off the rails, I can hit the board for 4 damage whenever I please. Great combo with Darien and First Response.

Deafening Clarion is weak, though. Firesong and Sunspeaker would be much better for the deck.

Magma Phoenix?