Felix caresses the back of his wrist, where a tattoo the size of a fingernail is visible in a pale white pattern that few would notice unless they looked at it thoroughly and carefully.

The pattern is actually an ancient magical text circuit that hides a small space within.

In this space is a spare wand.

After all, the pattern is so small that there is not much space to hide anything. The ancient magic circle is closed all the time and can only be unlocked if the conditions are met.

The only condition to open it is by smearing it with a blood of his own.

This is his most hidden, and almost undetectable, backhand at the moment.

When he is at a disadvantage, or when he is disarmed, loses his wand, or even has his ring taken from him, this magical circuit will help him to turn the tables in his favour.

As long as he is not killed on the spot, he has a chance to turn the tables.

The ring on his left hand is shown in front light, and the magic circle on the back of his right wrist is hidden in the dark, a near-perfect combination of light and dark.

And now Felix is about to build his third cave.

This caution was not because Hogwarts is a tiger's den, or because he was prepared to do something dangerous, but because he knew that the day he became the Ancient Magic Professor at Hogwarts, he would be officially involved in the plot.

He knew that the day he became the Ancient Magic Professor at Hogwarts, his involvement in the Plot would become a reality, and with his meagre knowledge about the Plot, it was difficult for him to be foresighted, so he had to take precautions.

He doesn't believe in the so-called "fairy tales", he only believes in his own power.

But even if he didn't understand the plot, he still knew some of the most basic things.

For example, the adventures of Harry Potter in his previous life were made into eight films, one for each year, which is eight years in the wizarding world. This fits Felix's imagination: seven years of school adventures, plus a year after graduation to defeat the Death Eaters once and for all, no problem.

It's his very strict logical deduction.

Now that a year had passed, if nothing else, Voldemort would be utterly destroyed in seven years.

Felix was slightly relieved by this thought.

He is certainly no match for Voldemort now, but there is no guarantee about the future.

As Felix plotted his future strategies, he left his house and walked through the streets of London.

Half an hour later, he stood at the door of the same dental clinic he had found earlier in January.

Felix pushed the door open and the bell on the doorstep chimed clearly.

A middle-aged man in a white coat poked his head out of the room, looked at Felix twice, and asked, "Are you here for a dental appointment?"

Felix replied briefly, "I want a filling."

The dentist nodded and led him in the direction of a seat, "Please sit down. My name is Will Granger, you can call me Dr. Granger."

"I'm Felix Hap."

Dr. Granger had him lie down in the seat and looked at Felix's mouth with a searchlight-like thingy with some confusion on his face, "Mr. Hap, your teeth are in excellent condition, very clean and neat, very evenly sized ..."

Felix pointed to the upper left side of his cheek, "I would like to fill wisdom teeth."

Dr. Granger was flabbergasted, this was an odd request, wisdom teeth are not very useful. He said sincerely, "Mr. Hap, I don't recommend that you fill wisdom teeth because ..."

Dr Granger then showed his professionalism by giving him a full 20-minute lecture on dental knowledge.

In the meantime, a young girl with fluffy hair, about 12 to 13 years old, came in and took a look at the two men, especially when she saw how Dr Granger kept talking and gave a look of "here we go again".

Finally, Felix had to interrupt him, "Dr. Granger, how about this, you can make me a tooth first, and I'll try it out and then decide if I want a filling."

Dr. Granger thought about it and thought it made sense. He took out a pen and paper and noted the dimensions of Felix's mouth. After tracing them on the paper, he soon confirmed the size and shape of the wisdom teeth.

He then went inside and started to work.

Felix looked around the clinic with interest, particularly at the small glass case hung on one of the walls, where magnified models of the teeth could be seen through the glass.

As he looks around intently, a confident voice appears on his left.

"A filling isn't the best option, especially for a disposable wisdom teeth."

Felix turned his head to look at the young girl, and then heard her add, "It hurts."

"It hurts? How much does it hurt?"

"A hole will need to be drilled in your cavity with a small drill, then the same hole will have to be drilled in and screwed back in place with your artificial wisdom teeth."

Felix suddenly got a bit of a toothache ...

And the little girl's sermon continues, "Even if you get a filling, it's not a permanent fix. On the contrary, a damaged cavity is more vulnerable to damage, and if you have bad oral habits, it can lead to decay and plaque, causing the original tooth to loosen and fall out, which must be repaired... ..."

"Stop it!" He already had the image of it.

Although he could use magic for repair and pain relief, now his mind is traumatised.

Looking at Felix's uncomfortable expression, the young girl tossed her long, fluffy hair and ran off to the corner to read a book, seemingly in a happy mood.

Nearly twenty minutes later, Dr. Granger came out again.

In the palm of his hand, he held a silvery-white tray with a man-made tooth that had been polished and finished.

"It looks great, doesn't it?" Dr. Granger complimented himself for his craftsmanship.

But Felix simply nodded his head, intimidated by what that little girl had just said!

As Dr. Granger had advised, he tried out the artificial wisdom tooth, without drilling or wrapping the wire, of course, just to test the comfort level.

"It's great!" Felix praised. "But I've decided not to have any fillings."

"Really? You seem to have made the right decision." Dr. Granger was happy for the client rather than upset that he was missing out on business.

But the client made a new request, "I'd like to buy this tooth as a souvenir."

"A souvenir?" Another strange request thought Dr. Granger, and even the little girl who was quietly reading a book glanced at him.

"That's right, a souvenir."

"All right." In the end, Dr. Granger only charged for the materials.

As Felix walked out of the clinic, Dr. Granger still felt something strange in his mind and he muttered to his daughter, "A very strange visitor, won't you say, Hermione?"

Hermione Granger looked up as Felix disappeared around the corner, shook her head, and went back to her book.