Do Flash Duel character abilities supplant main actions?
Jaina's Charged Shot ability is used at the start of a round, and doesn't supplant the normal attack during your turn. The designer, David Sirlin, answered this question here,


  Q: After using DeGrey's ability Spectral Pull or Push or Jaina's charged Shot, do you still take a normal action for this round or is the special ability your action for this round?
  
  A: Those trigger at the start of your turn, so you do them then you do the rest of your turn. Nothing says it replaces or prevents a combat action, so you can still move or dashing strike or whatever. Using Spectral Pull and then attacking during the same turn is legal and a powerful way to use it. It's especially good in the dragon raid mode.
  
  Note that the dragon does have a card that triggers "instead of his main action," so that ability really does prevent him from doing a main action later in the turn.