An effective auto-cast for the Invoker at a late stage of the game includes three key spells: Meteor, Blast and Cataclysm (a very powerful Sunstrike using Aganim). To use this combination, you must have level 18, as well as the items Aganim and Refresher. With this method, you can confidently attack opponents one by five, without fear of losses, especially if you activate the BKB. For the convenience of activating the first two skills, assign the Meteor to key 1 and the Blast to 2. Good luck in the game!