A fun hypnotic idea I've been using recently is the concept of a Mind Lock.
The concept is rather simple. There is a lock on the subject's forehead, and I have the key. I slowly insert the key, and when I turn it all the way to the right with a click, the subject becomes completely incapable of waking up while in trance. However deep they go is permanent until they either fall asleep, have an emergency, or I undo the lock.
This gives you a lot of fun routes you can take to mess with your subject.
You can do a count down, but occasionally start counting up, which doesn't work. However, when you start counting down from that higher number again, it keeps dropping them. Continue until they're knocked out, you're satisfied, or both.
You can suggest the idea that fluxuate in and out of states of trance constantly, and that since they can only go down and not up, that they will keep sinking down naturally.
You can tease them with the idea that trying to wake up takes effort despite it not working, and keep using the trigger to drop them deeper down.
However, my favorite use is just in a long term hypnotic teasing session.
I had a voice chat where one of my cute friends was playing the roguelite Balatro, and I used the Mind Lock on them with a simple rule: any time they used the discard button, they would drop a bit deeper into trance.
They kept stubbornly avoiding discarding any cards and eventually lost, and then I added another rule, that if they lose, I'll drop them much deeper than a discard.
They slowly had to concede, round after round, tactically choosing to dumb themselves down a bit in order to avoiding getting sent down much further by a loss. It didn't work. They discarded four times and lost, and I sent them down hard. I told them they had two chances left before I lock them down there for a long time.
Each game was shorter than the last. They were excessively drooling before the second game ended. I don't think they even wanted to win the third.
One last fun thing you can do, if you clarify that you turn the key to the right, is to do trance denial by turning the key to the left. When you do that with a click, someone cannot drop into trance at all, only rising up.
If someone is desperate for your control, you can mercilessly tease them by all their triggers and fun being taken away.
There's plenty more you can do with all of this too, but these are just some ideas. Happy hypnotizing! ^v^