Any and all feedback is appreciated, sideboard is a work in progress
Latest Update 11/5/2018 - Limited main colors to Red and White with the Chromatic Lantern and Navigator's Compass for Chamber Sentry & Nicol Bolas, The Ravager. SLightly adjusted the mana base to allow for Bolas to be cast without fixing and added 1 Seal away to sideboard and removed 1 damping sphere.
This deck is built to maximize the -2 ability for Karn, Scion of urza. It plays lots of early artifacts like navigator's compass, treasure map, voltaic servant and chamber sentry.
Navigator's compass and chromatic lantern fix our mana, add to the artifact count, and allow chamber sentry to be used to it's full potential. Also the compass allows us to play our buddy lands untapped even without a mountain and the life gain is often very relevant.
Voltaic servant synergizes extremely well with treasure map (allowing it to flip faster), the lantern by untapping it and leaving up mana for other uses, or by just untapping one of our artifact creatures. Also it is a decent blocker with the 3 toughness.
Chamber Sentry is amazing in this deck as a recursive threat, but also because it just fills out the curve wherever necessary, it can be a 1,2,3 or 4 drop using the normal mana base. Once you have a navigator's compass, chromatic lantern or treasures, it can be a 5 drop and becomes the recursive threat all decks hate to see. You want the opponent to use their counters/removal on this instead of our top end threats. The fact that it also doubles as repeatable damage to any target is a huge plus as it allows you to play around settle the wreckage and to shoot down problematic creatures, or just to get value from it even when they try to remove it(most of the time). Don't be scared to shoot things down with this early, as it generally always comes back late game, i.e. a turn 1 sentry kills a llanowar elf immediately to say the least. You almost always want to play this on turn 1 or 2 if possible, removing their first threat or even just being able to trade life points with the aggressive decks early is good.
Turn 2 and 3 you mostly want to be playing Treasure Map, then Chromatic Lantern or Sarkhan.
Karn is best here when he can just make karnstructs that are generally 4/4 and above. If Karn comes down on turn 4 and you've played at least 1 artifact per turn before this, he's making 4/4s otherwise even a 3/3 is decent. At worst he's drawing you cards and finding you lands/action which is what you want if he's not making threats that control the board.
Rekindling Phoenix is a great must be answered threat, that keeps coming back. Verix is again another threat that can win the late game if it is kicked. Nicol Bolas is just a good card that we can flip pretty easily into his planeswalker form. Demanding Dragon is just another big threat that can swing the game. Sarkhan is here to rummage and find what you need, ramp into verix or demanding dragon, or just be another wincon if he can ultimate. Shalai, Voice of Plenty is just a decent threat that adds a layer of protection (for Settle the Wreckage especially) and possibly pumps the whole team (this slot is still being tested, but so far I like her).
The deck is rounded out with lots of removal for early threats: lava coil, justice strike and banefire/fight with fire to finish them off if necessary. Fiery Cannonade to stop the go wide decks and Arclight Phoenix Decks. The burn spells are so good because you've generally got them low on life with your threats, and while they spend their turns trying to answer your threats you build mana/treasures to finish them with Banefire or fight with fire.
Sideboard:
Banefire, Inescapable Blaze, and Carnage Tyrant are for the blue control matchup or matchups where you want to side out creatures to turn off their removal spells.
Seal Away and damping sphere are here almost exclusively for the Arclight Phoenix Matchup but have other applications as well.
Ixalan's Binding is for problematic permanents you just need to go away and never come back (teferi, niv mizzet, any lords, etc)
Deafening Clarion for extra Sweepers or for when Fiery Cannonade is not effective
Sorcerous spyglass is for planeswalkers, or other problematic activated ability permanents.
