How much do lategame ADC crits actually do?

I want to actually calculate the damage of a lategame ADC crit. So what's a good build?

This gives +230 AD. Your average late game ADC gets around 98 ish base AD, so that's about 328 AD in total. Runes usually add another 8 AD, totaling to 336. This means crits hit for 840 raw damage.

As for picking a target, I'll just use Tristana. She has about 82 armor with runes, 73 base and 9 bonus. With 42% total bonus armor pen and 7% base armor pen, the mitigated armor is roughly 68 and 5, totaling to 73. This means Tristana will take 57.8% of the damage from the crit, which is 486 damage. With these numbers, it would take just about 4 crits to kill a Tristana, and given 80% crit chance, it's very likely that only 4, possibly 5 autos are required.

But let's also add in energized bonus magic damage, which, given that Shiv crits, is 520 bonus magic damage. Trist has around 50 MR with the runes I use, meaning she takes 520 * 0.667 damage, which is 347 magic damage. With this in mind, Trist is very nearly, but not actually killed with 3 crits.

And also these numbers will be a tad bit higher as Battle Trance kicks in, but the number of crits required to kill remains the same.

Now, if we look at a more likely target that an ADC will be hitting, like an Assassin, we can look at Zed as a target. Zed doesn't always run armor runes, but more often just runs MR runes and HP/lvl. This puts his base armor at 86.4. With our 7% Armor pen, we will have a mitigated armor of roughly 80, and Zed will take 55.4% physical damage, or 466 per crit.

As for magic damage, Zed will have 90.5 with Merc treads, meaning he will take 52.5% of magic damage, and thus take 273 bonus damage from the energized crit. With Zed's 2555 health considering he has , it would take 5 crits to kill Zed. With 80% crit, we can expect that to be around 6-7 autos.

But what if Zed got tabis instead of Mercs? Well, then his armor would be 116.4, 86.4 + 30 bonus armor. With 42% Bonus armor pen and 7% base armor pen, this is mitigated to 98 armor, meaning Zed takes 50.5% physical damage, and crits will thus deal 424, but with Tabis passive it will end up being about 382.

Now, Zed will have 65.4 MR instead, meaning he will take about 60% magical damage, and thus take 314.4 damage from the energized crit. With these numbers, it should now take 6 crits to kill Zed. We can reasonable expect this to be 7-8 autos.

TL;DR: With a lategame build, as shown above, it should take an ADC 4 crits to kill an enemy ADC(Trist used as an example here), as crits do 486 post-mitigation and energized crits do an additional 347 magic damage... Against an assassin with Mercs(Zed used as an example here), it should take about 5 crits, as crits do 466 and energized crits deal an additional 273 magic damage... Against an assassin with Tabis(Zed again), it should take about 6 crits, as crits do 382 and energized crits deal an additional 314.4 magic damage. Feel free to leave any feedback, like if I made an error in calculation or anything else.