How do you make a state that attacks enemies/bosses/monitors/etc?

I'm trying to create a good custom character for the first time, and I've come across a problem I have every time I try this: I don't know how to make a state damage objects. I've searched on the internet, on the wiki, tried plagiarism, but never found an answer. I've tried RadiusAttack, but that doesn't do anything to monitors. I've tried looking through the blockmap and damaging everything there, but it doesn't feel right, and the player still takes damage sometimes.