“You.” We can see from Isaiah 33:12 that the “you” here in Isaiah 33:11 refers to the hostile nations that desire to destroy God’s people, but they will not succeed.
“your breath.” This is the reading of the Hebrew text, although there is a variant reading, “my breath,” which has been picked up by some of the English versions (cp. NAB; NASB). It seems certain that “your breath” is original. The enemy planned to consume God’s people, but their evil plan was self-destructive, and resulted in their own destruction. God is righteous, and He has set His laws and His judgment in such a way that on the Day of Judgment the wicked are destroyed as a consequence of the evil they have done. In a very real sense, their own “breath” destroys them. However, it is much more than just their “breath” that destroys the wicked. The Hebrew word translated “breath” is ruach (#07307 רוּחַ), and ruach can refer to a large number of things, including wind; spirit, and breath. It also refers to the natural life of our fleshly bodies that is sometimes referred to as “soul;” and it includes the activities of the mind such as people’s thoughts, attitudes, and emotions. Thus, the Hebrew text is saying that what the wicked do, what they “breathe out” if you will, their evil thoughts, attitudes and emotions, will result in their destruction. [For more on the usages of ruach, spirit, see Appendix 6, “Usages of ‘Spirit’”].