This is a really cool deck, and really cheap at that. It looks like you have this pretty well thought out, but if you are willing to take any suggestions I have a couple cards that fit the strategy to a degree, and also would give you an alternate win condition of sorts, if your geist isn't cutting it for some reason. Even though it is really high on your mana curve, Bruna, Light of Alabaster might be a good alternate creature to hit them with, just because it is tougher, and has flying and vigilance, as well as synergizing well with enchantments like unquestioned authority to block freely. Moreover if you were to add Celestial Mantle to your deck, it would also dramatically increase your sustain potential. Another effective method of sustain could be Angelic Chorus, as it would gain 4 life for you every attack phase at least. I know all of these are really high on what looks to be an intentionally low mana curve, but it is just a thought.

I do have a question about how your combo with sundial and resonator builds you an army of angels though. could you explain that part to me? thanks

Qolorful, thanks for the comment. I can activate Strionic Resonator to copy Geist of Saint Traft's triggered ability which results in two Angel tokens entering the battlefield instead of one. Then, after the damage step but before the end of the combat phase, I activate Sundial of the Infinite to end my turn and exile all the triggers on the stack. This means that the "Exile that token at the end of combat" effect doesn't resolve and the tokens never exile.

Oh that is actually a cool combo, thanks for explaining

This is a really neat deck. I love the synergy with the Sundial, Resonator, and Geist.

I am working on an Azorius Control deck and thinking about switching to him as my commander. Wow.

what about Invocation of Saint Traft?

Athraithe while Invocation of Saint Traft has powerful effect, it does not provide any form of evasion which Geist of Saint Traft needs to enable his attack since he's just a 2/2 otherwise. I do not play this deck in a Voltron style. I do not like to attach multiple Enchantments to Geist of Saint Traft at once because he is so vulnerable to board wipes and sacrifice effects, so I prioritize those which provide evasion.

One of the strongest aspect of playing GoST in duel commander are the artifacts that can allow you to cast him on turn 2. Ramps after that are not that important.

Consider things like:1. Jeweled Amulet almost 0 reasons not having it. Allows T2 traft is a huge threat clock before most counterspells are ready.2. Mox Diamond3. Chrome Mox

On the latest update, duel commander starts at 20 life and very likely, you'll encounter more burn decks (Zurgo, Vial/X) which has crazy low curve. Stock up on your low cmc counterspells such as below (no 1-3 almost nearly mandatory)1. Mana Tithe2. Force Spike3. Spell Snare4. Spell Pierce5. Blue Elemental Blast or Hydroblast if Zurgo is plaguing your meta

Lastly, I think your land count is very low. In DC, tempo decks generally do not want to miss land drop + threat in the first 4 turns, which means they usually play 39-40 lands and no ramp before 0 mana.

Remember, turn 2 dropping signet means 1 turn skipped of not dropping threat and not keeping your counterspell mana open.