Tristana does not count. She does not have the burst that other champions with reset abilities and she's squishy. So even if she gets the reset it's not like she'll insta pop you like other reset abilities can. So, aside from Tristana, why are no other champions allowed to get resets on abilities?
Done253 votesBecause Assassins use a "get in then get out" play style. Hence why Kha and Eve's movement skills get reset on kill.
EnvyDragon3 votesDepends how you define ability resets.
If you mean the full cooldown refresh that Kat/Kha/Trist/etc get, then those are kept as limited as possible because of the exploitation factor. On assassins, that refresh is often necessary because their engages tend to also be their escapes. It rewards the assassin play pattern: do it right, get the kill, get away. Didn't get the kill? You are now out of position, and are probably going to die.
The reason full refreshes aren't as common on non-assassins is that if you have this happen in teamfights, and a strong ability becomes available again each time the champion gets a kill or assist, suddenly this champion turns every slight advantage into a win. Again, look at Katarina. Imagine if Vi or Xin Zhao had that.
There are also "lesser" ability resets, where the cooldown is reduced by a certain amount for performing an action, or for using the ability in question a certain way. We see this a lot with champions who want to deal consistently damage over a duration 
or who are encouraged to use certain abilities in certain ways 
. This means you can have a character who is very, very powerful if you can reliably accomplish their goal (constantly using Lucian's passive gives you a ton of tactical mobility, picking up lots of Q kills as Annie in lane gives you more frequent stuns) but it still leaves room for failure.
TL;DR: An ability with a 20-second cooldown is usually very, very strong. An ability with a 2-second cooldown is usually very weak but spammable. An ability with a 20-second cooldown and a reset is the kind you should be given as a reward for playing well, and not all champions need (or have room for) that sort of explicit reward mechanic.
Sire Hippington3 votesso tristana does not count because she'S not a assasin?('She does not have the burst that other champions...')
what about darius ult? Irelias Q? Annies Q? Kallistas E? or don't they count cause the abillity it self needs to do the kill for reset?
Also, assasins need to use mobillity to reach a target, and mobillity to escape again as they are shortranged and squishy, so atleast resting mobillity fits thematically and gameplay wise very well to assains.
Cloud2731 votesso tristana does not count because she'S not a assasin?('She does not have the burst that other champions...')
what about darius ult? Irelias Q? Annies Q? Kallistas E? or don't they count cause the abillity it self needs to do the kill for reset?
Also, assasins need to use mobillity to reach a target, and mobillity to escape again as they are shortranged and squishy, so atleast resting mobillity fits thematically and gameplay wise very well to assains.
Oh boohoo. They're not completely perfect so that means they suck right? And learn to spell please. I feel like my IQ dropped after reading this post.
7ha7guy7772 votesi want to know the thought process behind giving resourceless assassins resets
360D3GR3SS1 votesFiora Is not really an assassin. I mean she can be considered one, but her kit is not efficient enough to be classified as an assassin.
FiendOfOne1 votesFiora. Darius. Irelia.
SmokingPuffin1 votes Witness true resets!
Hayaishi1 votesKalista?
FiendOfOne1 votesOh, also, AP Tristana CAN and WILL burst you down really fast. She's intense.
Cloud2731 votesDarius does not get a full reset. He actually has to spend mana in order to use his ult again and he only gets it for a few seconds. If it was a true reset he would have the cooldown removed completely. Akali or Katarina by contrast get either an extra ult or their ability cooldowns reduced. Also Darius and Irelia have to kill enemies using specific abilities, or else they don't get the reset. Katarina, Akali, and Yi can kill an enemy with ANYTHING and they still get the reset. And they still have to pay the mana to use their abilities again (unlike Akali and Katarina)