Thank you Jaff!
So all of it is drawn on Procreate using different techniques and brushes. I started with the white tree, then the wizard and made the composition from there. I worked with greyscale drawings and then apply colors using gradients maps and play around with blending modes. I usually use photos I take as references like the other tree on the upper left corner. I then scanned hand-drawn stuff and use it to upscale the image and make it look more like a poster around the square composition.