What do you want to see in LoL?

I don't quite follow your logic. Of course Shadow Fiend and Fizz aren't alike in their play style, however they are high risk, high skill, high reward.

That's not what i meant, but fizz to me isn't high risk compared to a SF, fizz has a slow and knockup and abilities that allow himself to be positioned and escape.
Shadow fiend has nothing of that sorts ontop of being super squishy, ganking him with smoke(the item that changed how effective SF is) will cripple him to a point where his BKB(Core item on SF) will be so late that he wont make the difference he's meant to make.

A bad start for Fizz is crippling, since by nature he's an assassin. Assassins need to keep up and excel in experience and gold to be able to do enough damage to destroy people.

Of course, that's the nature of an 'assasin'.

Fizz's abilities to perform in this role are varied, and it depends heavily on you flying around with E later in the game. And Fizz has deficiencies as an assassin. He has very bad options for sustain. However, his early game is where he gets his headstart, since his passive allows him to ignore minions somewhat, and his W absolutely destroys people in a land of lvl 1 auto-attacks.

And shadow fiend doesn't have anything earlygame, he has problems all along the game until he has a BKB. His base attack damage is so bad that you can out-deny a SF easily until level 4+ unless he is using all his mana on razing, thus pushing his lane and making him even more gankable. Running a duo mid also completely shuts him down. He also has a low attack range letting melee heroes lane against him without having any problems.

I don't think you citing that last bit of information works to your advantage. If anything, you're more arguing for a handicapped champion that otherwise fulfills your qualifications. Play Evelynn if you want to. She gets stopped by 400 gold, snowballs off of kills/assists (ult), and she's squishy as hell, making positioning and opening with her a vital skill.

I don't want a handicapped champion. Far from it.
It's incredibly hard to explain. And evelyn has nothing of what i am personally looking for.
Getting an almost 90% secured kill on SF costs 100 gold.

Fizz is high risk in that you have to be in melee range to deal damage while not having the protection of a typical melee champion. Therefore, he has many counters (Easy to stop). Since he's also squishy by nature, relying on maneuvers to "mitigate" damage, he can die really fast if things go wrong. Usually with assassins, if you don't maintain your advantage, the other team is still able to win the game, and late game is generally not where you want to be as an assassin in games with competent players (easy to knock off course). Easy to gank... well, not really xD I suppose you could bait him though.

And i see what you're trying to say, i just don't see fizz as quite as high-risk, he has the same problems that a lot of other champions have.

Fizz is high skill, mostly in his E. It's not quite long range enough to allow Fizz to punish casters if they attempt to throw spells at him. On the flip side of the coin, if you are close range, it tends to get very difficult to react in time when they decide to throw spells at you, primarily skillshots. Skillshots tend to have CC, and stuff like Morgana's Dark Binding can ruin you day easily. A true master can react and pole at point-blank range. Fizz's Q also supplements his title of associate juke master.

And coming from DotA fizz to me is a lot like tiny in terms of risk vs skill vs reward.
Tiny has the same problems fizz does and the same role early on.

Fizz is high reward. Assuming your opponents are the dimwits you painted them as, Fizz can easily get to the point where he can pick off the other team's carries. Even if they aren't, you just feel guuud outplaying them, since some of what he can do is a direct counter-response to what they do, more so than "oh I move a few feet to dodge your fireball".

Well, i know that fizz can be high reward, but for example, if a shadow fiend finishes a BKB and boots by 15 minutes he can force and win almost any teamfight against most lineups. But getting a 15 minute BKB is almost unheard of and if you don't have it by 20 minutes it's getting close to too late for you.

A quick question: do you like playing Shadow Fiend as it is? What about if item counters were nonexistant/less egregious to him?

I love shadow fiend because pubs do not use his counter.
If i were to play in public games where people used smoke often, no i wouldn't find him fun(That came out wrong, i would find him fun but i wouldn't find the constant being shut down fun, and since pubs generally lack coordination i couldn't rely on a team which i would be able to rely on when playing with friends, thus still making him incredibly fun to play), getting shut down would be too easy and is not what i'm looking for and even though i am fairly decent with SF, i am not at a level where smoke ganks wont destroy me.
If smoke didn't exist he'd return to his old status and be an incredibly boss semi carry whom is incredibly hard to stop.
Smoke gives your team a special kind of AOE invis that disappears if you get in range of a hero or tower, this is to stop wards from keeping anyone safe. The chinese SFs were pretty much ungankeable and were so hard to stop because of how easy they are to farm with and how crazy mid-game damage they have.(if his ult hits point-black it can 1HKO anyone from 20 to 40 minutes into the game.)

A shadow fiend needs to know exactly how his razes work and exactly what the range is. They're visually misleading and don't quite show the range they have, knowing that the first raze can hit a small area behind you, for example is something most people won't know.

 Spoiler

But i just used SF as an example, though, it's not about him specifically, he's just the strongest midgame carry there is in DotA due to his skills(Imagine a champion that has the passive of BT with a cap of maybe 100 damage ontop of minus armor aura and a lot of massive AOE burst. But due to how easy he is to shut down, you rarely see him.

The kind of 'high skillcap' i was looking for was something invoker-ish, where a player needs to know the cooldown of all 9 side-spells ontop of what order to invoke them in and what combination they require and what level his quas, wex, exort is to know how effective the different spells are.

Didn't mean to make it into a SF vs fizz.
I do think this thread is heading into a bit off-topic, which i apologize for.