Basic attack simulator.

[Bridge]

You may want to take advantage of ActionScript's excellent randomization functions and incorporate some actual dicerolling (since you wanted critical hits). It's pretty easy to implement because ActionScript gives you everything you need. Just specify the limits for each attack and use the random function + modify the damage based on the outcome.

EDIT: Also, just a little cosmetic suggestion: I recommend changing the font and not using such obvious gradient fills. They are classic noob design decisions.