Every MoF boss has 4 exclusive drops, 2 normal, 1 which can drop on normal but scales with item rarity and one empowered only that also scales with item rarity.
Ravenous Gloves is the first Item of it’s rarity and drop table.
It got officially confirmed by the patch notes in 0.8.3c that it is supposed to be a random and boss target drop:
But also by the creator of that Item on his reveal livestream.