YOU HAVE TO WAIT FOR THE SWIFTCAST ANIMATION TO FINISH BEFORE YOU USE THE NEXT SKILL.

LOOK AT YOUR BUFF BAR. THE BUFF FROM SWIFTCAST WILL NOT APPEAR UNTIL THE CASTING ANIMATION FINISHES. IT'S THE SAME REASON WHY YOU CANNOT USE MULTIPLE INSTANT OFF-GCD SKILLS IN BETWEEN GCD SKILLS.

WAIT FOR ANIMATION TO FINISH!