All your looping triggers should be turned off when there are not units to pick. Turn them on if they are off and you add units to the groups.
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Set bomb_creation_point_2[1] = (bomb_creation_point[1] offset by 0.00 towards ((Facing of (Picked unit)) + 90.00) degrees)
Remove this line since it's useless and create the bomb at Set bomb_creation_point[1]. Don't use an array thoug, more about that next:
You are using 5 point type variables and two point type arrays, when yo only need to use two non-array point variables. Arrays take up more memory, get rid of them, you don't need them.
You are setting
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point = (Position of (Picked unit))
three times in "Create Bomb" trigger. You only need to set it once.
You're using Facing of (picked unit) many times. Save it to a variable, and use the variable.
There's way too much effect spam. I don't think you should create effects every 0.10 seconds.
The tooltip is too simple.
The casting unit doesn't get credit from the kill, also doesn't get exp.
You could make it a hero ability or hero ability version and make it support levels.
Make the spell easily configurable.