Reprisal is good to combo with different mitigations, but i tend not to mix it with rampart and the -30%.
Arms Length would be an example of a better combo. some enemies might have missed you during its short window, or started a ground AoE/self buff, right as u pressed it.
so imo, comboing the -20 from arms length with reprisal is better than comboing it with rampart. (not that it makes a huge difference or anything. Plus reprisal will be up far more often than arms length)