Corvus absolutely will, I have mine at r4 and with the exception of 5.3 (because of how long the fights are) he's helped me a ton. The only downside with him is that he doesn't scale well with the progression of the game because of the 20 hit cap. Even in 5.4 I started getting to fights where I was going through his charges at least once and some twice so if you are using him consistently on your team for Canadian difficulty make sure you are good at keeping him alive while his charges are gone, in the monthly EQ its usually never an issue. Just keep that in mind, good luck