Need help on making this kind of quest.

[steelknight999]

Is there a way when I click an icon on the unit a quest will appear much like in gaia's retaliation where you click this green check.

 

[Nichilus]

I guess the icon is an ability that does nothing. If so, you could just use a trigger to detect when unit begins casting an ability, check if the ability is the one you clicked and if yes, grant the quest.