Boosts damage by 50% when user has less than 20% health. This offensive boost seems to apply to almost all forms of dealing damage, including sorceries, pyromancies, miracles, special attacks and abilities and even bows.
Analogous to the Clever Rat's Ring from Demon's Souls. The Red Tearstone Ring sees much less use than its counterpart due to the absence of an insurance spell such as Second Chance. However, extra skillful players may get use out of this ring yet as its damage boost is very significant. The ring stacks with other damage boosters, so particularly suicidal players can try using both this ring and Power Within for a dramatic, but short-lived, boost. The Red Tearstone Ring can be used well with the Blue Tearstone Ring if the player has high defense and vitality.