Star Dragon is outdated
- No reliable consistent pinpoint damage
- Increased amounts of removal each new set
- Unreliable removal protection
- More and more "Unkillable" units are being released
- Some removal protection has been introduced, although it's mostly redundant (Song for a Hero, Blessing Errata), and incomplete (Does not address things like Mystere, Dion, Shelby SS combo, Catira, etc etc etc.)
The way the file is set up causes the file to be binary in the extreme. Although Star dragon is a great unit with tons of damage potential, the fact that it level seven and drains Sphere levels causes it to be extreme SP consuming. The SP drain makes it hard to field other good units, and the fact that there are many types of removal further taxes the player's resources. The high level makes it hard to play Star dragon in the first place. Playing requires you to build your file around him, or you will not be able to get the best out of him.
This is also in addition to the fact that more and more cards have "Unkillable" traits now. The greatest offender in my opinion is Dilate. Star dragon's Counter only does 45 damage max. With 60 HP, a single star dragon will never be able to kill Dilate. Meanwhile, dilate is free to kill Star dragon.
On the other hard, if the player manages to keep Star dragon on the field and keep him there, it is likely he will win. He can potentially deal tons of damage each turn, and has 120 hp.
When the end comes, and enemies are rushing in from all sides, I will be at your right hand.