The cellar/dungeon area is quite extensive, so I'm not sure where you are, and some of the areas are a sort of maze where you can only go through one path, so you'll be able to see through the bars but have to go the long way round to get to the other side.
The key to the Star Chamber is given to you when you find the right person, but that's usually happened before you reach the point where you use it. You may have to backtrack and collect it. Have you met anyone else other than the vendor? There should be at least one more significant NPC down there, and I'm not counting Swammy as he's a mini-boss monster.
Transmute is Nature Magic.
The cellar/dungeon area is quite extensive, so I'm not sure where you are, and some of the areas are a sort of maze where you can only go through one path, so you'll be able to see through the bars but have to go the long way round to get to the other side.
The key to the Star Chamber is given to you when you find the right person, but that's usually happened before you reach the point where you use it. You may have to backtrack and collect it. Have you met anyone else other than the vendor? There should be at least one more significant NPC down there, and I'm not counting Swammy as he's a mini-boss monster.