@Ghostcrawler The very long discussion about crit
Ghostcrawler - Crit is another example, but that's a very long discussion. :)
Introduction
Hello Mr Crawler, I am an aspiring game designer, and a huge fan of league. I love the communication the designers of league give and I love their explanations of their decisions, it's highly educational and have helped me tons to grow and learn myself.
I've been in discussions about RNG loads of times with people I've worked with, and with friends. In the past league have had bad implementations of RNG here and there, which is not fit for this type of game really, but most of that have been abolished. RNG's last stronghold is the quasi-random crit. The discussion about crit is quite big, since it's core to a whole class of champs, and it's a base mechanic. Discussing changes to the foundation of the house when you already have built a freaking mansion IS huge, but please let us have this discussion.
How does crit work and why is crit an issue?
Crit in league of legends provides additional scaling for auto-attacks, to make them scale better into late-game without being too oppressive early game, and not have a linear scaling. Each autoattack there is a certain % chance that you deal 200% damage, which can be increased to 250%. The % chance increases if you do not get a crit, and goes down when you get a crit, to even out the chance of you getting a crit, and not make it completely random. The aims is to even out the number of crits to your crit chance stat. This is to ensure you do not get 10 lucky crits in a row with 10% crit chance, or get 10 non-crits in a row with 70% crit-chance.
Now why is this still an issue, even if there is a derandom-mechanic added to crits in league? Because crits are too binary, either you hit a crit or you don't and the difference in damage is simply too big. In the big picture for your DPS crit is fine, like if an ADC fire at a tank in a teamfight, the random factor is not important since there is so many hits you are required to hit on the tank before the tank goes down. On the other hand if an ADC hit another ADC in a late game teamfight, while having phantom dancer
and infinity edge
, for a totalt of 55% crit chance it's not implausible in the 2-3 hits that ALL are crits or ALL are non-crits. The difference there is that in one scenario the enemy ADC might survive and in the other it might die, and the only difference is luck, no decision making, no skillful usage or anything, it all boils down to luck, with a big difference in outcome. Especially if you pit two late game ADC against each other, if both get off as many shots on each other, whoever get most crits off wins then. Even if it's quasi random it's still random.
As I described earlier for extended auto-attacking crit is fine, but what extended in practice means depends on your crit chance. If you have very high crit-chance most of your attacks will be crits and it's fine. But if you have sub 10% crit, you get 1 crit every 10 hit on average. This is a lot of attacks, especially early on, and if that hit happens to be on an enemy champion early on it warps the lane quite heavily. It's part of the reason some people run 1 crit rune, to get that super low-cost miniscule crit-chance. In the rare cases you get a crit during the right time it gives you a huge advantage, while the cost of adding that rune, is very low. If you get this crit early in the laning phase, it is worth 2 auto-attacks and hit about 25-30% of the HP of an enemy, it's enough for you to win that early fight, zone the enemy off minions, and start to snowball the lane. It can be enough for you to win the late if you're a good player, and there is no decision making based on it, there is nothing you rely on, and you do not play differently until it happens. It's just luck, nothing else.
Example: In the 5th game between C9 and TSM, there was a decisive teamfight which won TSM the game, with both ADC dueling each other. Wildturtle's Tristana hits Sneaky's Corki 3 times with his autoattack, and all 3 of them are crits and kills sneaky. Tristana get a reset from that and kills Meteos too then. At the time Tristana had a
and a
for a totalt of 45% critchance. If instead turtle would've gotten 0 crits in that fight, he could have possible lost the duel and Corki could have killed him, using rockets and sheen-procs. It's hard to know how it would've played out though.
https://www.youtube.com/watch?v=cub6GwhhmlU#t=52m38s
Why is crit good as it is? 
Big damage numbers are fun. It feels good to hit a crit, because you deal tons of damage. For normal and casual game the random factor is fine too. There is nothing at stake, and it's okay if the game is not 100% skill based. If it's possible to make the game more exciting and fun, even at the expense of being able to show your skill it's not that big of a deal. For a game that is played as a sport, that have million dollar competitions, that is supposed to show the epitome of skill, it's not okay to keep as is though.
Possible ways of fixing this 
There is a few champs that is highly dependent on crit.
have it as his passive, and much of his lane interaction is based on how much rage and thus crit he have.
uses his pistol for massive burst attacks based on crit usually. Kinda similar to an ADC, but more focused on burst instead of DPS.
scales off crit extra much using his passive and in his mid-game build he mostly removes the random factor on crits.
Those champs will probably require some tweaks to them, but might work even with a new crit-system. Having a crit-system at all is kind of important as ADC-scaling is based on it, and to remove the crit-system would throw very many things up in the air.
Solution A.
The easiest way to fix crit-system and still have autoattacks being based off 4 multiplying scaling parameters would be to simply make crit system flat multipliers of damage. Instead of having a crit-chance you simply multiply the damage by X. So with 30% crit chance in new system your autos simply deal 30% more damage. Then for item like
which increases crit damage from 200% to 250% it simply increases bonus damage by 50% of what it is. So if you have 30% you get 45%. If you have 10% you get 15%.
In all forms of DPS calculations the crit-system is unchanged then, the only thing that is removed is the random. It IS less exciting to have crits then, but they never had any decision making attached to them before either, but only a simple math calculation about which item is most efficient for your current build and playstyle.
Solution B.
Instead of crit being a chance, it fills up a bar/number. Once it reaches and 100, 100 is removed and you will hit a crit next attack. If this number would be shown, crit would be a mechanic of its own to keep track of very similar to
headshot passive. It would also create similar situation to caitlyns passive were enemy tries to keep away while you have a crit stored, and caitlyn tries to get the crit onto them. If it was hidden it wouldn't really add a mechanic and have people react to it as much as it simply removed the randomness from it completely.
Solution C
This is the ramp-up system, it's not like the current system at all, but is slightly similar to the solution A. If you have "crit chance" you get stacks that increases your auto-attack damage. Each stack would be worth say 10%. The number of maximum stacks is determined by your "crit chance". Example
would give you 1 max-stack, while
would give you 3 max-stacks.
would increase the value per stack, so each stack is worth 15% instead. The stacks then rapidly fall off if you don't autoattack, similar to
minigun-stacks.
This would add some gameplay to crits, while removing the RNG.