The word available is a neutral word. Depending on how it is used in a text, it could convey a negative or a positive feeling. The word "dangerous," on the other hand, always conveys an exciting and scary feeling. The word "lost" similarly conveys an idea of desperation and worry that can prove very intense. Finally, the word "last time" conveys a feeling of finite opportunities, which can also contribute to developing an intense feeling.
The literary term would be an oxymoron. Oxymorons are “a figure of speech in which apparently contradictory terms appear in conjunction (e.g. faith unfaithful kept him falsely true ).”
