Same mods for any melee but Reaper take it to the next lvl
Reaper prime is insane ez red crit high damage and fun to use with both stance but you have to forma it 4/5 times to be able to switch between both stance which is the only downside i think, but it's worth it in my opinion. You can switch riven for Attack speed mod or more critical damage with Gladiator mod. (You don't need a riven for reaper , it will melt everything regardless but if u love [Reaper Prime] like I do, Riven is worth the investment and If you got RANGE on your Riven like 2+ KEEP IT and reroll for more range if you want, you don't need CC/CD, RANG IS FUN I promise)