Novice Scripter need some help/ideas

[kruqnut]

I am currently trying to write a single weakaura so that when I cast starsurge, Starfire, or Wrath, a text indicator will take a snapshot of the current balance power when I start casting so I can work on timing for more damage in eclipse. Basically just a little guide to perfect my rotation and track how im doing.

My problem is making a trigger that fires when one of those 3 spells are started to be casted(and one is an instant)

I can't seem to get spell_cast_start to work and im not sure how to properly pull the values that I need to check the conditions to make sure it's firing properly, or how to get a static value because what i've came up with gives me a dynamic value that follows my eclipse bar at it's current state

Any help would be appreciated.