I sure do love League of Legos right now, yup 3228 dmg from Rengar in 0.28 seconds is my absolute favorite way to die. Zero counter play being one shot in a quarter of a second under my inhib tower is such a blast. I sure am glad Riot is doing literally nothing about damage being stupidly high this preseason. (Pure sarcasm if you can't tell)
This preseason is literally one shot or be one shot.
You mean that 19-2 Rengar? You know the one that was probably on fire and had a full build while you weren't even at your third real item? That rengar that you built nothing save 600 hp for? Totally riots fault, you didn't even have armor. I can agree damage is high, but don't blame the fact that your team got stomped by a fed Rengar you built nothing for and was literally 5 thousand gold ahead of you by the end of the game. What did you expect?
Edit I was looking at teemos' gold not rengars. Rengar was closer to 8k gold ahead.
tl;dr: If op itemized properly, they would have lived.
For context: OP was playing nexus blitz as LeBlanc with no armor against a 19 kill Rengar that built lethality and crit, and was presumably on fire. I can't imagine why rengar did a lot of damage.
Just for fun, let's do some calculations. At level 17, LeBlanc has 78 base armor, or 39 after subtracting for the lethality Rengar had. With Zhonya's, that would have been 123, or 84 after lethality's armor reduction. Before accounting for armor, Rengar would have dealt 4483 Damage
x(100/(100+39))=3228 .72x = 3228 x=4483
Now with Zhonya's:
4483(100/(100+84))=x 4483(.54)=x x= 2421
Leblanc at level 17 has 2000 health, plus the 600 OP had from Rylai's and Morellonomicon. That's 2600 Health.
If you had just build zhonya's before rylai's, and had a 
, you would have lived. At that point, you probably would have been good to build tabi over sorc boots, which would have let you live with even more health.
(not sure how much damage he did with autos, but with 20 extra armor and 12% reduction from his auto and Q, could have been as little as 1934 damage)
This is a problem with you not knowing how to adapt your build accordingly, not with the game.
{quoted} This preseason is literally one shot or be one shot.
??? Things like 
used to one shot even faster in the past
What the other guy said
I understand the frustration, but Rengar feast or famines based on champ select. Either you have someone that can stop him in his tracks. Or you have a bunch of free kills.
Honestly, it's unacceptable. Not only is one-shotting unhealthy by itself, have a one-shot in anything less than 1.3-1.7 seconds is absolutely disgusting and it's the most toxic thing to play against.
if ASSASSINS are fed they can have 0 counter until they hit mid/late game which usually leads to people having armor/magic resistance to stop about half of their damage from build alone, if your an adc you should have some more protection late game thanks to your support peeling you like he/she suppose to. If your a top laner, your kit with your build alone should help you survive some of the damage if not a lot of the damage they try to throw at you. Rengar has a lot of damage if he get his target like he suppose to, prevent that or he will do a crap ton of damage, even if he gain his extra damage that don't mean he unkillable, team are there for a reason relay to them and communicate and work as a team, this is not solo player, and learn the damage ratio and build accordingly.
if you are good against his damage and want a easy counter messure pick up a bruiser or pick up poppy, her W make it so he doesnt pounce you from his ult+passive combo. Rangar like other assassins has strong "all-in" combos but they also need to save half of their kit to escape from being killed, if they don't the team making this solo kill almost less effective in a teamfights.
Quick note: grabbing items like 
are perfect protection for assassins who come to kill, waisting their initial burst which allows you to have a second chance at survival.
Nexus blitz. Enough said
<---- these save lives
probably not the best example. Rengar in his prime could kill you in literally 0.00 or 0.01 seconds, not even trolling. There are several videos you can find lol
