A couple of notes:
Push more color. The entire piece reads as grey, when you have a huge amount of opportunity to use the entire spectrum. A forest is full of color, browns, reds, ochres, blues, violets, etc. Visual interest involves color, and this could use more.
A forest is full of living things, I’d add more plants and grasses and bushes and vines and such on the ground and around the trees - that area needs more detail, anyway. Piles of stones doesn’t work, unless your environment is rocky, which trees like that would not grow in.
The squirrel is cute, but it feels unnecessary, and the branch.
The background trees need more texture.
Your focal point is the light glowing from the tree, but the narrative is the interaction between the figure and the tree. I’d use the light from the hole to lead the eye to the figure.
Druids generally did not wear plate armor, lol. They were around long before that kind of thing was going on, and they tended to wear robes and costumes typical of ancient England and Ireland. They were priests/shaman, not warriors.
I would explore different angles. I would do the scene from ground level, looking up at the tree, looking past the druid’s back. That would create a more ominous feel, and set up more tension between the figure and the tree, and give the tree more of a feeling of being very large and imposing.
It’s an okay start, hope this helps.
PS - generally, you don’t sign a painting until it’s done, and really, it’s a bit big, it’s very distracting. The eye sees letters and numbers first, and your signature draws the eye away from the scene. Signing a painting is a personal decision, so feel free to disregard this.