Lol? You are clueless.

No, shadow flare is a 250 potency AoE. Besides 3 stacks of AF BLM, name one other AoE that is that strong and not on a huge timer(Dragonfire Dive).

It doesn't take 13 seconds for them to start ticking. They're still ticking while you're setting up.

Slow? After 3 GCDs we can use an off-GCD 300 potency attack.