Casting spells on a group of units?

What is the easiest/best way to go about doing this:

CasterGroupX casts AbilityX on UnitGroupY.

Whats important, is that UnitGroupY gets AbilityX ASAP, wether every caster in the CasterGroupX casts the spell is not important.

Say for example, you had a group of 12 footmen, and wanted them to "instantly" have bloodlust. I have a group of Shaman right beside them, how do I get the Shaman to cast bloodlust on every single footmen?


Also - Is there a way to toogle auto-cast on/off in the editor?