This is an updated version of my pet "fun" deck, Citadel Artifact combo. This deck is for Best of 1 only - although I do not believe it would be impossible to play in Best of 3, the strategy is linear enough that it would suffer more from sideboarding than it would gain, and I believe it benefits significantly from the element of surprise - which would be lost in postboard games.

The usual kill is to have Citadel + Saheeli or Bad Saheeli (Sai) and just start rolling cards off the top. You'll end up with ten-ish tokens in play and assorted utility artifacts. Eventually you either hit Tezzeret naturally, or use Symmetry to put him on top and cast him. His uptick followed by a Citadel activation is a nearly-guaranteed OTK.

The most important cards to have in your opener are: Saheeli, Citadel, Symmetry, and Treasure Map. Sai is a poor man's Saheeli as mentioned, but he and Teferi both buy you a good amount of time which you should factor into your mulligan choices. If you somehow end up with both Tezzerets in your hand, mulligan. You don't want to have to hardcast him.

Treasure Map is part of all our best draws because it guarantees you Citadel mana the turn it flips, as well as fixing your draw to help you get there. The first copy of Symmetry you draw will always be earmarked to fetch Citadel - use your intuition as to when is best to cast it (usually either turn 1 or the turn before you have Citadel mana).

TIPS:

- Because you almost always use Tezz to kill, try to remain above 7 life (for Symmetry + Tezz). This most often comes up with deciding when to crack Orazca Relics - if you wait til you actually see Tezz/Symmetry on top to crack, you'll draw the card (often leaving it uncastable). So be aware of life and use those Relics proactively.

- While we're on Relic, remember one of the most powerful tools at your disposal while going off is using Saheeli downtick to turn a "useless" servo/thopter into a Treasure, Relic, Amulet, Mox or Map. To do this, you will need to actually have the original artifact in play, so remember to try and use Saheeli each turn before you start cracking the real thing. Remember that Mox is legendary, so float mana before you make a copy. Don't get Saheeli killed if you can't finish going off right away, but remember she's a 4-of and hitting duplicates while comboing is real. Use each one before you play the next. Also, if you somehow end up with enough permanents, you can activate citadel, then turn another artifact into a second citadel (legend ruling the original) for an immediate 20 damage.

- When Citadel + Saheeli is out and you topdeck a Symmetry, you can use it to chain through all the remaining copies in your deck to cheaply up your artifact count before using the last one to find Tezzeret.

- In addition to buying time vs. creatures and protecting your Citadel from countermagic, Teferi uptick allows you to cast Symmetry in your opponent's end step, which makes the card almost foolproof. You can also use him to squeeze extra mana/tokens out of Mox Amber by tapping it, bouncing it, then replaying it and tapping again.

- It's usually worth delaying your plays by a turn to make sure you use Maps and Amulets to hit land drops in the early game. Always be playing to the Citadel turn, which means having mana to cast it as well as finding the card. However, if your hand is shaping up well consider not playing/activating your artifacts so you can use them to either trigger Sai/Saheeli once they arrive or to move lands off your topdeck once Citadel does.


MAYBEBOARD:
I have yet to get many games in with the deck since this latest rebuild, so there are a few things I'm not locked in on. 

- The manabase (including the number of shocklands, since both life total and hitting untapped lands most turns are very important. BBB for Citadel is non-negotiable but Black is nearly useless otherwise, a certain number of basics are important for searching out, and our artifacts add a hard-to-quantify amount of fixing)

- The life gain (Previous builds had 4 Deploy to aid in combo turns, but Scheming Symmetry has drastically reduced the amount of our deck we need to play through before we hit Tezz and win. Navigator's Compass is attractive for fixing reasons, but is a bad card in general. It's hard to say how many "life positive" cards we need with Symmetry around, especially when you consider the cards that could replace them often stop us losing as much life pre-combo)

- The interaction (Teferi has taken the precious flex slots here as the synergy with Mox and Symmetry is too good to ignore, and he protects against the worst possible blowout of having Citadel countered while not being dead vs. creatures. However, if aggro pressure gets too much playing Moment of Craving or Gideon's Sacrifice (budget fog) are both possible)

- Teferi has caught my eye for now, but I would also consider exploring a Sultai build where green fuels Root Snare and better ramping/fixing with Gift of Paradise and possibly Deathsprout. Green splash could certainly go deeper with cards like Bond of Flourishing, but with Symmetry I think the core of the deck is consistent enough to not need it.