How does Channel work?

I'm running out of skills to remake for my map, and I wanted to try some skills using the Channel ability, but I'm not sure how it works...

If I want a pulse PB AE (see Crystal Maiden ultimate in DotA), how would I create that with Channel, so it breaks when the unit stops channeling?

Or maybe Channel isn't used for this ability.

Either way, I just want to know what type of things Channel is good for, and what all the different "Data" does in the GUI.

Have you tried EVENT_UNIT_SPELL_FINISH?

To make the Maidan Ultimate in DotA, they used starfall, with no damage and no effects.
They used 2 triggers, 1 to begin the loop, the other to carry on looping, the looping trigger runs every 0.1 seconds, it creates a dummy which novas itself in a area. It checks if the order id of the casting unit is the same as starfall, i used this method is my chain lightning, which was channeling

Isn't there a box in the ability editor you can tick to make the ability channeling?

No, everything like that is hardcoded, if you want a channeling spell, the spell you base it off must be channeling