[b]Lexicon:[/b] Altranor is the name of the kingdom, (and the capital city, and the king's castle), and it has existed for hundreds of years, at the very least. Chymistry is a thing (as mentioned under the martial and technology header, that's a collective term for alchemy and early chemistry. Actual English term) and magical potions can be a thing if you want them to be, otherwise it's mostly just superhumanly good medieval chemistry. Magical items (potions or otherwise) still require magic to make, though - spells and dead magical creatures.

What exactly you use isn't all that important, just remember not to make yourself any more powerful than anyone else. Also, don't be surprised if powerful characters are able to shake off poisons and such that would kill lesser men.