Channel.
Channel is comfortable spell for many issues, At first it has various differend options, it can be invisible, visible(ect), it gives opportunity to show effect for given amount of time, ables user to set animation time (anything you wish) and last, the most important:
Enables user to create all types of abilities:
Passive/Active No target/Active Target unit/Active Target Point.
It also gives chance to add variations like Tiny's Toss in dota.
Its ability based on channel with choosen option: Target and added AoE.
Look at this:
Data - Art duration - Total looping time for graphic effect.
Data - Base order Id - Here we stop for a while.
In warcraft3 each spell has differend ID (indentification number) and thats why unit can cast multiple spells without bugging them. If we put few spells with the same ID on the same unit, there will be a lot of strange events going on whenever it'd try to cast any.
You can make as many abilities based on channel without having bugs as you want - but remember that you have to set different ID for each one of them. To do this just click on the mentioned field, from list choose random ability and press enter although, the unit you wish to give this ability to, can not have spell with this ID already.
Data - Disable other abilities - Disable/enable other abilities command card.
Data - Fallow Through Time - Animation time, duration of looped "channel" or if unit doens't own such, "stand" animation.
Dont use default 180 sec, it means unit will stay and channel spell for 3mins.. basicaly doing nothing in meantime except for looping "channel" animation.
Set to 0 if you want 0 cast animation, but for smoother effect keep 0.5-1.5sec delay.
Data - Options - Here you choose options about your ability (like: if you want it to be visible check on 'Visible')
1) Visible - Enables icon image to be shown in unit's interface.
2) Targeting image - Enables AoE indicator to be shown in-game, if field Stats - Area of Effect has been customized.
3) Physical spell - Allows target all units (even magic immune ones) except for ethernal units - invurnable units can't be targeted still.
4) Universal spell - Enables casting spell on all units, including the ethernal ones - invurnable units can't be targeted still.
5) Unique cast - Prevents from multiple ability-cast when more than one unit with given ability is selected and ordered to cast that spell.
Data - Target type - Important field - choose how your Channel-based spell should act as.
1) No Target - It's automatic spell, like Thunder Clap. Activating requires only pressing the ability's icon.
2) Target - Requires single target to be cast. Specify targets allowed in Stats - Target Allowed.
3) Point Target - Spell activates after selecting and pressing LPM on map's area.
4) Target or Point Targer - The mix of two types above. Can be activates in any of mentioned ways.
If you wish to give AoE component, fill field Stats - Area of Effect.