I'm sad to say that this series declines as it continues. The first book, Poison Study, was a perfectly delightful read that left me literally obsessing for the these sequels. Unfortunately, with such an emotional anticipation, the books disappointed.
My feelings are mostly due to the lack of frequent interaction between Yelena and the chief of security in Ixia/super assassin/the love of Yelena's life, Valek. I can't even fathom why Ms. Snyder thought the series would be any good if she took Valek out of the majority of the book. I am, rightly, annoyed at his absence and would be much happier with the series if their romance had continued in a similar fashion as in the first book.
No matter, the series is still enjoyable and I'm glad I mustered my way through these subsequent books because somewhere in the second book, we're introduced to Opal, who is the fascinating star in Maria Snyder's newest series - Sea Glass and Storm Glass - which I am happy to report only gets better as the series progresses.
My rating of Magic Study & Fire Study: 6 - Good. Solidly good.