Karune talks about the Immortals and how they differ from the original Dragoon in Starcraft II.
Karune: At the moment, if Immortals were to be anti-air, they would be far too powerful. In terms of balance, we really want to make sure you don’t have one type of unit be able to kill all others. Currently, the Immortals are vulnerable to rapid fire units and air units. On the other hand, they absolutely own armored units, including Stalkers and Siege Tanks.