Ratchet, Field Medic (EDH / Commander) [Revision 3]

The object of this deck is to gain life and cheat big Threat creatures into play using Celestine's Healing Tears ability.

Discard/Mill Engine: These are the most important cards in the deck. Draw cards and discard Threats so that you can cheat them into play using Celestine's Healing Tears ability. If your opening hand doesn't include one of these or a Tutor, you should consider a mulligan.

Copiers: The main downside to Celestine's Healing Tears ability is that it only triggers once per turn. These cards aim to fix this. They're important, but they won't work well if you don't already have a Discard/Mill Engine. Since there are so few Copiers, you might consider tutoring for these cards before you have much life gain.

Double Strike Equipment: Granting Celestine double strike increases how much life you gain each turn, allowing you to cheat bigger Threats into play with Celestine's Healing Tears ability. Many of the More Life cards serve the same purpose, but they're not as easily tutored for since they're not equipment. Double strike also allows you to rack up commander damage. These cards combo particularly well with Mask of Memory, and Skeleton Key.

Royal Guard: Celestine can't use Healing Tears if she's dead. These cards aim to keep her on the battlefield. As a bonus, Celestine can reanimate nearly all of these cards without any support.

Threats: Discard these, especially if you don't have the mana to cast them. Cheat them into play later with Celestine's Healing Tears ability.

Lifegain Loop: Archangel of Thune, Heliod, Sun-Crowned, Nykthos Paragon, and Cleric Class are among the best cards to combo with Celestine. When you to gain life, put counters on Celestine, the next time you attack with her she'll gain you more life, you'll get more counters to put on her, etc. It's a good loop.

Other Lands: Severally lands help you gain life. Note that many of these lands are artifacts too. This enables Inventors' Fair.

Misc. Notes: Without any support, Celestine's Healing Tears ability allows you to bring back an up to 3 mana value creature from the graveyard. Because of this, nearly every key deck component (i.e. Discard/Mill Engine) has at least one card that is a 3 or less mana value creature. For example, for the Discard/Mill Engine, there is Stern Constable. For giving Celestine double strike, there is Silverblade Paladin. Nearly everything in the Royal Guard qualifies. For Removal, there is Skyclave Apparition. For Advantage, there is Esper Sentinel. For More Life, there is Serra Ascendant.