So you only need 11 buttons (helpful for controller), and 2 for pet place and return (pet is permanently summoned). 3 combo single target attack, and 2 combo AOE attack, with 1 ranged DoT attack. Rez and 1 shield (changes depending on level guildhest/dng etc). One button for instant ATMs to prevent finger/wrist pain.

The key here is you never need to look at your hotbars and can concentrate on the gameplay mechanics and party members.