Use the Tyrael botbase (it allows you to move, face, and target things while the routine handles all your spells and skills). Configure the routine to do what you want it to do, and by routine I mean Insanity. Within the configuration of Insanity you will see options that will have the routine handle targeting and facing and movement (though movement won't work with Tyrael, so don't enable it). While using the routine it will face your target, and it will automatically switch to a new target as long as you are in combat. It will not pull new targets. It will only attack targets attacking your group or tank. This will only happen if you have the "Targeting" option enabled in the config. It's pretty simple. The options are very self-explanatory.