DRK CDs are meant to be stacked. That's why you have two with only 60s recasts and a potential 4 cross-class cooldowns. Shadowskin and Shadow Wall by themselves are fine but anything else should be paired up with something. (Dark Mind+Conva, Dark Dance+Foresight, etc.) Also DA Dark Mind is OP as fuck on bosses with magic based tank busters. If you stack it with Shadowskin or Shadow Wall that's 50-60% reduced damage. Up to 70-80% with Reprisal/Delirium up.