Wood spirit

The wood spirit sends logs to the bank for you, and gives you a small chance of receiving higher level logs, sent directly to your bank. It is acquired by drinking a Juju woodcutting potion when woodcutting.

One might find a wood spirit while woodcutting. There is a 1 in 10 chance per log cut while the potion is in effect, it will send logs to your bank for a little while.