My hotbar is set up so that hitting any 3 consecutive keys will get Combination to come up. There is only one spot on my hotbar where this isn't true. I than have my Combination on my alt-3 key so it easy to hit. My setup is, starting from '1' and ending on '=', is as follows: Waking Dragon, Roundhouse Kick, Striking Cobra, Five Rings, Rising Dragon, Frozen Palm, Silent Palm, Arctic Talon, Rising Phoenix, Charging Tiger, Crescent Strike, Dragonfire. I know my hotbar really well as I have had it the same way for almost a year now. This makes it easy for me to trigger Combination. EDIT: If you swap the position of Arctic Talon and Rising Phoenix than any 3 consecutive keys will cause Combination to trigger.
Even with every set up listed, its still a royal pain in the grass to consistantly use, I bug the ability weekly for the Non Crit aspect and the time frame being almost impossible due to server lag. Everyone please bug this ability or feedback it