Potions Grandmasters were rare in the south coast, and at that time, Leylin was only a rank 1 Magus. Thus, he needed to avoid doing things that would leak his secret and lead to trouble.
But the central continent posed no such problems. Even the Ouroboros Clan alone housed a few reputable Grandmasters, not to mention the entire continent.
Furthermore, Leylin had already become a rank 3 Warlock, and his strength now was leagues ahead of what it was before. With Gilbert as his back-up, he had no cause for fear. Thus, it wasn’t much of a problem to reveal a bit of his prowess in the field.
It was still important to keep it a secret on the whole. Leylin’s Potioneering ability was honed over many years by personal tests and A.I. Chip simulations. In addition to the Chip’s assistance during the act itself, he’d reached a level of skill that bordered that of the most respected Potions Grandmasters, a mysterious and unfathomable realm.