If you are a WHM without Swiftcast, you are holding back your team at endgame

[Moirear]

Flash doesn't have a cooldown timer, it's only limitation is your MP. Swiftcast and provoke both do, and both are situationally useful but should not be needed except for mistakes.

Swiftcast allows you to use cast faster overall, whether you're running the role of dps or healer, because you can regularly cast a spell instantly that would take longer otherwise, be it a Medica or whatnot. And good luck tank swapping or peeling enmity without Provoke.

Please stop making up excuses like "these abilities are only good for mistakes."

It's weaksauce, and the only excuse for not having them after a certain point in time is laziness.