Put the tree stump in a container filled with enough water to cover and in 12-24 hours, the tree stump will start to crack and your unicorn will being to emerge.
Once the tree stump is broken entirely, add more water and the unicorn will continue to expand.
After 48 hours, you may want to move your unicorn to a larger container and watch it continue to grow.
WARNING: CHOKING HAZARD - Small Parts. Not for children under 3 years.