This is my take on a classic deck that still goes 5-0 in Legacy League. This is the mono-red version. It is my dream to build and play this in paper, as although relatively cheap for the format, the pricey cards don't look like they are getting reprinted anytime soon.
The main combination is Grindstone + Painter's Servant
. When Servant enters the battlefield just name blue, activate grindstone targeting your opponent, pass the turn.
Of course the deck is built around this combo so cheating it into play with Goblin Engineer and Goblin Welder is nice. Tutoring for Servant with Imperial Recruiter is a typical play pattern (hence the deck's namesake). Every other creature in both main and sideboard is fetchable with Recruiter as well, and sometimes taking a circuitous route rather than going straight for Servant is the better play.
The synergies turned on by naming blue with Servant are Pyroblast, Red Elemental Blast, and Jaya Ballard, Task Mage; it is worth being wary of Force of Will insofar as naming blue turns the opponent's lands and artifacts (or otherwise dead cards) into blue cards to pitch. (Note that in the rare circumstance where Servant and Mycosynth Lattice are both on the battlefield, whichever entered first will have its color-changing effect overridden, which may turn off Pyroblasts or turn on an opponent's Force of Wills)
The deck features a toolbox sideboard turned on by Karn, the Great Creator giving lots of options even pre-board. It can also can get the combo pieces from the sideboard or exile if need be. The option for Mycosynth Lattice is there for when a complete lock is needed, and Wurmcoil Engine in case combat is the only path to victory. The notable non-artifact cards in the sideboard include: Irreverent Revelers, which is useful against artifact-based stax strategies and tutorable with Recruiter; Surgical Extraction, which is useful both against dredge, other combo strategies, and decks which are un-millable due to Emrakul, the Aeons Torn-like effects; and Fiery Confluence, which has a great deal of flexibility as artifact or creature removal.
Something to try experimenting with (as sacrilegious as it may be) is removing the Recruiters in favor of some more removal (i.e. Lightning Bolt), or leaning more into the prison aspects of the deck with Blood Moon and Magus of the Moon. Also, Blood Sun might be better than Blood Moon since it doesn't turn off the extra mana from Ancient Tomb and City of Traitors (it actually negates the downside of City of Traitors), while making the enemy fetch lands completely worthless. It also draws a card, which is a significant upside.
As far as "budget" options go the City of Traitors could be cut for more Lotus Petals, Snow-Covered Mountains, and Great Furnaces, and the deck can run on as few as 18
lands thanks to Simian Spirit Guide. For MTGO it is possible to cut a copy or two of Karn, the Great Creator without messing the sideboarding strategy up too drastically.
