Painkiller Illrigger questions

I'm about to start a new character in a running campaign, but I don't know if I understand all the class features correctly:

The invoke hell feature gives 2 options. Grand strategist and Punishment. Grand strategist requires no action, does this mean I can use it only on my turn as a free action or at any point during combat? Punishment requires only a reaction when taking damage. Can I use it on all kinds of damage and just blast that straight back? I don't see anything in the app limiting it's uses like once per short/long rest, up to proficiency bonus or class level. Seems kinda broken.

Would love it if someone could way in on this.

But you only have one invoke hell to do either effect, isn't it?

The text says 'the damage they dealt you', so as far as I can tell via the well established language of 5e RAW, it's meant to be option A. I definitely see the argument for option B, though, it does make sense. Just keep in mind that if you decide to rule it as option B, it is a slight buff to the Illrigger.

Like micchon stated, if you have options for "Invoke Hell" using those options burns a use of that ability.  Like a Cleric's "Channel Divinity" may have a few options with differing action requirements but each use counts against your total.