Leaders and units - who casts what on whom?

[baboune]

Hi,

I was wondering if a leader casts support spells on his troops primarily or if it targets any group?

Let me give you an example: A Coral Queen commands 2 Groups of units, and a Deep Seer commands 1 set of units.
In combat, does the Coral Queen casts Fanaticism on one of the 2 sets she commands?
And if so what group is first selected?
Or does she target any Groups of units?

Any ideas?

Thanks