Since, unfortunately, the issue of "defending yourself" being confused with retaliation and counterflame is still something of a pertinent issue, I feel that this is fair enough timing to bring up some experiences of my own that prove that you don't have to counterflame to be "defending yourself", and that you don't have to rise to every single slight against you.
And, while it obviously needn't be said, I will preface that this won't be the usual fare of reminding people to _Mute, Report, & Move on_ as is the PB motto. Instead, I'm going to share a recent anecdote so that people can see the way that I, as a player, respond to flame and similar such stressors in a match, and hopefully consider a more tactful approach to future altercations in League.
And, of course, the last bit of preface is that, for the sake of individual player privacy and compliance with the rules, the only Champion I'll give is the one I played for the match; the flamer(s) will be generalized and characterized by their faults, not any identifying information - whether that be screenname, champion, or whatever else.
So, with all that out of the way, let's set the stage;
The other day, I had played a string of ARAM games for the sake of earning an easy Hextech Chest. In one of the matches, I got Karthus as my Champion, and while our team was largely AP, I was confident to play Karthus regardless. The whole of Champion Select goes by without anything noteworthy, and the match begins.
Some ways into the match, someone (To be referred to as "Build Dictator", for this anecdote) starts badgering me about how I'm playing Karthus, telling me that I need to "go in".
I promptly ignore him, and continue playing Karthus as I would. That is to say; staying roughly in the middle-ground and harassing enemy Champions with _Wall of Pain_ and peppering them with _Lay Wastes_, with _Defile_ being used if/when enemies dove near/on me, and of course, _Requiem_ being used post-mortem or whenever I was safe and saw someone at critically low health.
(Sidenote, there was a genuine moment of banter between me and an enemy with one of my _Requiem_ casts, which I'll probably bring up as a bonus later.)
The match continues, and the only other irritation comes from a second player pinging my items without comment (As you can guess, they'll be referred to as "Item Pinger".), until later in the game, Build Dictator starts bothering me again, saying something along the lines of;
**Build Dictator:** goooo iiiin
**Build Dictator:** karthus is so easy, just max e, dive in, and do massive aoe damage
**Umbral Regent:** It's a little late for that, considering I've already maxed Q and W by now.
**Build Dictator:** lmao what
**Build Dictator:** who tf goes q and w in arams
I believe that Item Pinger said something too around this point, but it was too small and petty to really remember. The Build Dictator continued to flame me, blaming me for the loss (as one does when someone doesn't build precisely to your specifications, right?), but I didn't say anything to them before or after my comment about their timing on telling me to max _Defile_.
I didn't need to defend my playstyle; I don't play Divebomb Karthus, I play regular Karthus. I don't need to tell someone off when they insist I play something I don't intend to play - I just ignore them. If they want to play Divebomb Karthus, they can do so if/when they roll Karthus, but I am not them, and I have my own playstyle.
And I didn't need to respond to all of their jabs and insults; when he asks "who goes q and w in arams", he already had his answer. I do. There's no point in answering a question he already knows the answer to.
And I don't need to respond to him pinning the blame on me for not playing how he wanted me to play. I know I didn't cost us the game (the enemy team had three tanks and we didn't have any AD - generally speaking, we were pretty much doomed from the start, to no fault of our own. Just bad luck.), and his insistence to that idea was pretty much just a childish temper tantrum. So I let him throw his fit and sulk and blame me - he's just going to forget the match anyhow, so there's no point in trying to agitate him further.
I defended myself tactfully; I merely pointed out that, at level 16, telling me to max any specific ability is a day late and a dollar short, since at that level, I'd already maxed three abilities - two Basic Abilities and my Ultimate. A simple reminder of that fact and the assertion that I've already decided my playstyle was enough.
Naturally, I reported him for his flaming (as well as the Item Pinger for their negativity, although I probably should've added a comment to that. Oh well.), and continued about my ARAM spree. I didn't rise to every slight, I didn't answer every question or prodding, I simply made a tactful assertion and was done with it; nothing more needed to be said. Defense successful.
And, for bonus points, the banter anecdote; somewhere early on in the game, I had used my second _Requiem_ to try and finish off the enemy Leona, and failed. The exchange went as follows;
**Umbral Regent:** Leo, did your W give you enough MR to survive my Requiem?
**Umbral Regent:** Frig.
**Umbral Regent:** That's tilting.
**Leona:** you'll get me next req
_This_ is banter. It's light-hearted, well-meaning, and it's playfully competitive. It's not littered with insults or hate speech, it's just two players having some good fun - even as enemies - in the game.
So, there you have it; an example of what I mean whenever I tell people that you can defend yourself in chat without retaliating, or that defending yourself requires tact. I don't expect it to work for everyone, and I certainly don't expect people to readily follow my example; there are certainly a great many ways to respond to someone while being perfectly tactful, and this is only one example.
Consider this, then, as an invitation to discuss my example (Do you think it suffices as defending myself? Do you think that I misstepped/misspoke? Do you think I could've/you would've gone further, or would you have said anything at all, were you in my shoes?), as well as an invitation for others to share examples of their defending themselves without retaliating.
(And, of course, while _Mute, Report, & Move on_ is ubiquitous for these scenarios, I'm encouraging more discussion around actually defending oneself in chat.)
Hopefully, though, this example offers something to think about if nothing else.