A rift opens and a group of trees shuffle into the colosseum. They have gnarled, angry faces. - Tome of Encounters (RPA-Tome-SQ1-149)

Eating the fruit of a Treefolk will give your skin the physicality of bark;

After a few more bites, you feel a slight twinge in your stomach and a tingling sensation along your skin. You stare down and notice your arms have hardened, taking on the cracked texture of an oak tree. You grab your face and feel the same rough surface layered over your skin. Your flesh is tougher now. - Tome of Encounters (RPA-Tome-SQ1-150)

They commonly surround their adversaries and root themselves in place until their enemies are subdued and can no longer put up a fight;

The Treefolk surround you and you become entangled in their branches. The sky above you is completely blotted out beneath the shade of their leaves, trapping you in darkness. Their trunks press hard against your chest, crushing your ribcage. Like ordinary trees, the creatures now stand perfectly still. - Tome of Encounters (RPA-SQ1)

A group of Treefolk surround you in the Forgotten Forest if you try to cut a shortcut through. - Tome of Encounters (RPA-Tome-ADV7-2)

• Slash your way through them and forge a new path.
• Be crushed by their bodies as they push into you and freeze in place.

A horde of Treefolk are brought in to fight you at the Colosseum of Ashes. - Tome of Encounters (RPA-Tome-SQ1-150)

• Reduce them to splinters and move up in the ranks.
• They render you immobile and the games go on around you until they are removed.