Channel is quite a blessing. Though some of its fields may sound fishy, in fact it is a very good skill. Why? Because it is specially made to be a dummy ability. And it can have any order string, if you put the appropriate value in the data - base order ID.
Now, I'm not sure about all the fields, but here is my guess:
For options, Visible I guess that doesn't allow the caster to target invisible units (meaning that even if you have true sight you cannot cast it at them), Targeting Image I guess it works only for illusions, Physical Spell I guess it affects Magic Immune too, Universal I have no idea and Unique cast either. You should try them out yourself!
Follow Through Time AGAIN I guess (I'm not sure about it) that makes the spell channeling. Try to set its duration to 0.01, and see what happens. I didn't test it, but you can do these tests.
Visible - if set to off then the icon for the spell is hidden on the command card (can still cast with triggers) Targeting Image - will show the area effect target image (used with the area of effect property) Physical Spell - the spell can target magic immune but not etheral Univesal Spell - the spell can be cast on both magic immune and etheral Unique Cast - dont know
follow through time - how much time should the hero channel the spell. disable other abilities - this prevents the channeling from getting inturrupted.
