If someone was toxic to me can i be toxic to them

No.

No

This isn't elementary school, there is no "they started it first".

i would say yes, but every1 disagrees. still, i say yes, you should be able to be toxic imo.

No, you can't. That just makes things worse for the whole team. Mute the person and report them after the game.

No.

Don't even think about it or try it.

Yes you do have that right.

Don't complain about the consequences later tho ;)

No. Cause then the other 3 players on your team are also being affected by your toxicity

Nope

Nope, if someone wishes your entire family gets cancer and tells you to kill yourself, but you so much as call them "bad" in response, Riot will punish you too.

Should be able to.