In addition to being a creative take on a classic artifact creature, the piece also has a welcome undercurrent of levity, with a flock of white birds, presumably bothering the Servant in the tradition of their species, being sprayed with paint in an act of automated revenge
Enchantments There are a variety of good permanents you can drop that draw you cards on damage like Virtue of Courage, damage doublers like Dictate of the Twin Gods, damage triplers like Fiery Emancipation, as well as card that add bits of damage (and the ever key triggers for these cards in this section) like Mechanized Warfare and Roiling Vortex
Like most Magic: The Gathering cards, the value of Advocate of the Beast depends on a few consistent factors: its rarity, the printing and finish (regular or foil), its physical condition, and the set it was printed in (Magic 2014)
Just like Swan Song replaces a game-winning Omniscience with a 2/2 Bird token, most of blue's best removal swaps a permanent for a much less threatening creature token
Scarlet & Violets reorganization of pack contents mean theres a holo in every one, making them generic, and this has meant that for most sets of the era, getting anything better has been around 1 in 4
Shell also be great friends with Grim Hireling