Amber Ring

What we know

Intricately carved amber ring taken from necklace of executed Forest Folk druid at Wizard of the Wines (Session 24 @ 02:59:56)
Sildir alone sees pulsing red energy flowing inside the amber; strange glyph on the face (Session 24 @ 03:00:38)
Resembles Mercurio's amber Flute of Silence but with something unique about it (Session 24 @ 03:00:16)
Ring reacted to Sildir's vengeance when he cut down the druid (Session 24 @ 03:01:08)
Sildir pocketed it rather than wearing it immediately (Session 24 @ 03:01:41)
Hoar urged Sildir after the Tome of Strahd vision: "My champion. In your hour of need, don the ring. And seal our bond." (Session 25 @ 01:47:19)

Sildir heard a dark voice ("Take your vengeance") before the druid's execution—not Torm (Session 24 @ 02:58:12)