First of all, Blackest Night is amazing and you should abuse of it if you have the MP

If you are fighting just one group (3-4 monsters), you shouldn't need cooldowns. The best you can do is use Low Blow to stun enemies and keep killing

If you are going for bigger pulls, Blood Price and Dark Arts + Abyssal Drain helps a lot keep your HP up. Convalescence also synergizes well with this combo. You could pop Rampart as well to reduce damage taken

Anticipation is a good pick if you need a bit more of defense (parry is clunky, but it's worth the shot if it's your only option)

Shadow Wall is incredibly bad and I don't really see any real application for it because of the low duration. You shouldn't need Living Dead either. If it happens that you need to use it, just pull your internet cable and wait until the party kicks you so you can find a better group