hypnosis is primarily a tool of influence. It can be used to manipulate sensory experiences and bend perceptual frames.
You can do amazing things classes under positive and negative hallucinations meaning you take away a sensation that should be there or install one where none exists. This means taking away (or creating) sensations like heat and cold or pain and comfort or sounds and images.
It gets interesting when it comes to sounds and images because you can create blindness or create a visual hallucination like a green leprechaun. You can even evoke the sound of someone guiding you or talking to you.
Depending on the metaphors and stories you elicit you can create profound experiences with deep implications in learning and healing.
You can even use hypnosis to speed up or slow down physiological processes like heart rate or bleeding rate or wound healing rate.