The merchant grinned “Dear sir, I noticed you had your eye on that charm. Might I interest you in a little bit of its history? Of course I would. I will have you know, that charm has seen its way through many an adventure, and saved the lives of many of the adventurers therein. Legend tells that it was crafted centuries ago by Yurid Norcral, the greated Dwarven runesmith to ever live. Later it was said to have been enchanted by ancient Elven magics which have since been lost to the ages. Quite a rare find.”
The spirit of a creature trapped in amber cannot escape to it’s afterlife / next incarnation / whatever.
Such trapped spirits can be contacted by those who know the right rituals and magical power derived from them – typically the power to control one individual of that species.
Can by quite powerful if the creature is a colony insect (ant, bee, wasp, etc) – simply control the queen and you command the whole colony.