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.
The forests, the swamps, the lands lost to wilderness, fang, and willow. These lands are home to the creatures of wiing, tooth and claw. Some far more capable of fending off the hominids, others still, are less fortunate, falling prey to spears, arrows, and dogs. As the hominids encroach upon the sacred woodlands and miry bogs there are times that the thorns and vines are animated by the spirit of the land in order to fight. In this way the mysterious guardians are formed. In the shapes of wolves, bears, and many other greater and more terrible beasts, each with eyes of glowing emerald. Fiercely defending creatures of burrow and glade.