What is toxic?

What is being "Toxic" ? People tell me to go kill myself ect.. ect.. lots of rude and messed up things. So when i respond the best way i can to people trolling and just being rude in chat by asking them to do things in game i am penalized for this. Asking someone why didn't you do this or why didn't you do that? that is toxic ? while they are throwing slang at me and telling me to end my existence i tell them auto attack that tower or go to drake now and when they don't do it i call them bad for not trying or not understanding. i proceed to say things like go play bots. go learn the game better. u are throwing the game for us. go be bad somewhere else. I'm not being nice but am i toxic for this? when the target of my frustration is a person who is telling me to die and calling me useless and bad, while simultaneously feeding. Am i the one who is toxic for returning the favor? are we both toxic? should we both be banned? Regardless of your answer i know how riot feels and i know how they handle it. Still I'd love to here any thoughts.