This monster appears to have the best (Stud bullets+Influence)/(Cost+Upkeep) ratio in the game. It's the same as Steven Wiles, however once we put The Harvester to play, it's much easier to keep him with us because of ridiculously low upkeep.
Because of his trait, we can't take benefit from those high stats simply paying his cost and putting him at our home. Resigning from 2 additional dudes in starting posse may be painful as every shootout deck needs some cannon fodder in early game. These are a few cards I found which can be used to get The Harvester into play.
Two goods are designed to put Abominations into play, sometimes even during shootout: Clown Carriage and Soul Cage. There are also two spells: Raising Hell and Summoning. The second one appears to be created specifically for putting The Harvester into game as reduces his cost to zero and is of the same value.
There are also 3 action cards allowing to play The Harvester, each in different fashion: Recruitment Drive as effect of town square job, similar to Summoning; Serendipitous Arrival as support during shootouts and A Piece of the Action as Noon play.
I couldn't find any deed useful for our task.