SB delirium wouldn't even function in the current game design where the resource management has be standardized to either an "aetherflow" system or 50 gauge spenders. I really think they should bring back Dark Arts but repurpose it to fit the current design but retain the concept of augmenting your gcd/cds. Some examples of how Dark Arts could work in 7.0.

-60 sec recast 2 charges.
-Gives 3 stacks of DA when used.
-1 stack of DA is consumed when appropriate action is used.

examples of actions affected by DA:
-Unmend = changes to Abyssal Drain target aoe.
-Souleater = MP restoration, increased potency
-Stalwart Soul = restores HP, cure potency
-Dark Mind = Magic defense increased to 25%
-Shadow Wall = Reflect damage (similar to vengeance)

DA still functions similar to how it was previously but since you gain stacks, you don't need to press the button every time you want to buff something. It's all automatic and it just gets used up as you do your rotations. It also doesn't add to the skill bloat as it simply makes the current tool kit better. It's similar to TBN in that its a one-button-does-all type of thing.

Also TBN should be put to 2 charges and the MP cost removed.