Imagine a race whom have mastered the knowledge of black holes, at least a bit.
They've found a way survive, with their planet intact, inside the gravitation of the black hole without getting destroyed by it. (I know it is not possible for humans but in my fictional universe there are species which understand the universe a lot better then we do.)
Is there a way for the enemy to destroy the planets inside the black hole? I ask because all missiles or some cannon like the death star would be destroyed by the black hole and would the black hole also grow?
Let me explain the following picture: 3 planets are in the gravity pull of the black-hole but around each planet there is a safe-zone created by a much more advanced race, they even have something like wormholes in the safe-zone so they can leave the black-hole's pull. There is no way to enter the wormhole for other species.
If a planet gets sucked in by the black-hole, would the dismembered planet collide with the planets? I imagine the parts of the dismembered planet would rotate in a way people do in a funnel slide. I hope you grasp what I am trying to say.
Edit: JDługosz helped me understanding the horizon, please read his answer and make new suggestions.
How can they find the localization of these planets?
Which weapon would be enough to destroy them and what is the best way to destroy all three planets at once (So they can't prepare a defence)?
Would something like this hit the planets? But— I mean something with physical form, planets or a sun, but in the form of the example. Example