"In their wings, in their trees,
All things die, be at peace,
Cease all care, they are coming,
God of the forest, carry us."
— Prayer of the Forest God
The Forest God is, or was, supposedly the most powerful entity in the Forest, and was revered and feared by almost everyone residing there. The truth was not so spectacular - rather than a benevolent deity, the "god" was essentially an aggressive, violent beast, who showed contempt for it's devout followers like Godtender Brown.
Hundreds of years before the events of Lost Constellation, the god got into a conflict with the Huncher, who refused to give way as she wished to survive at all costs. Whilst it gave way to "peace," the Huncher decided to strike and poisoned the Forest God, with a poison brewed by the Kid, crippling and killing them. The god did not discover this until Adina, told them that fateful Longest Night, after which the "god" died immediately soon after.