For Stormgust skill_cast_db should be set like so:
89,<CastingTime>,<AfterCastAllSkillDelay>,<AfterCastWalkDelay>,<AnimationDuration>,<FreezeDuration>,<SkillCooldown>
1000 = 1 sec
1500 = 1.5 sec
Example:
if you want
Stormgust
15 sec cast time
0 sec delay of all skill
0 sec walk delay
5 sec Animation
12 sec Freeze duration
1.5 sec Cooldown
89,15000,0,0,5000,12000,1500