#dannan

If you are referring to what's brewing up on Griffith's feet at the last page of chapter 367, this isn't poison.

These things look like faces, so this is something that we are already very familiar with.

Remember in episode 366 that Casca's protection amulet by Flora was effaced when she saw Griffith (Guts' protective markings on his brand were also effaced by Slan during Qliphoth, so this is a thing that happens). So the same wraiths that so far have followed Guts at night are haunting Casca now. They are starting to show up at Griffith's feet.

It is also full moon right now, where magical energy is at its highest. If Guts also gets his protective amulet effaced for whatever reason, we might be in for a climax similar to the Birth Ceremony (it was in part caused by two branded people traveling together). Griffith's Maelstrom may contribute to this, but we don't know for sure yet.

While it's definitely not poison, whatever is going to happen is threatening Elfhelm's very existence. The Great Cherry Tree has lost all of its blossoms and Dannan actually collapsed, stating that something (the wraiths) will creep up from the earth.

It seems the cherry tree didn't die off entirely yet, so there might be hope.