This is a list of enemies that drop Tier 5 Rings.
Sort order is alphabetical, ignoring descriptors where it would separate otherwise similar enemies, and ignoring articles.
The enemies are:
Beer God
Cube God
Ghost of Skuld
Golden Oryx Effigy
Horrific Creation
Janus the Doorwarden
Lord of the Lost Lands
Oryx the Mad God
Oryx the Mad God 2
Pentaract
Skull Shrine