Viper is quite literally just press button that glows. The only time that ability icons might make a difference is is you care heavily about hitting the positional correctly. I struggled with the same issue until I just started following the ability that glows, it leads you through all the combos, even highlighting to use the buff abilities that have the lower time remaining so you refresh it instead of the one with more time remaining. Seriously, unless trying to min/max, do not over think it and just follow the glow.