The new jungle item in patch 5.13 Devourer is the key for this guide.
Devourer can proc on-hit effect every other auto attack. Fizz's w is on-hit magic dmg and it has % dmg over time. Fizz's q proc on-hit effect plus one normal auto. Fizz's ult increase all the dmg above by 20%.

PLUS, AD Fizz does decent magic dmg too. Every game, its about 55% physic dmg and 45% magic dmg(dmg dealt to champions). Not like AP Fizz, AD fizz does magic dmg by the Devourer's passive plus Fizz's w. AND THE TOTALLY DMG DEALT TO CHAMPIONS, IS CRAZY AF.

Pros:
HIGH DMG
Mixed DMG
TRUE DMG
INCREASED DMG FROM ULT'S PASSIVE
DOT DMG
EASY TO SKILL ANYONE EVEN TANK SINCE HIGH DMG

Cons:
No Burst like AP fizz
item reliable
will get aimed all the time, without E, die super fast for sure

http://www.mobafire.com/league-of-legends/rune-page-planner#&rune=369:9-262:9-263:5-319:4-381:3

PLZ FOLLOW MY RUNES FOR AD FIZZ PLZ

Max w first, then Q if u need more dmg, or E if u need to dodge more skills.

In this patch, the Devourer is easy to stack up. It requires 30 stacks to get into Sated Devourer. And it's not like the Feral Flare, the Feral Flare makes the jungler farm in jungle forever. The Sated Devourer stacks up with taking down large monsters and champion(+1), the RIFT SCUTTLERS(+2) and Dragons/Barons(+5).

It means u just need to kill one dragon with ur team(u dont have to be the one kill dragon) then u will get 5 stacks. And the Baron will get 5 stacks for Devourer too. And before u take dragon, u take the scuttler, u get +2 stacks from it.

So clear one side jungle camps(+3) and one scuttler(+2) and one dragon(+5). U just get 10 stacks in a few mins.

Also, as AD Fizz jungle, choose careful to clear camps or gank.
In first 5 mins, u will upgrade ur Hunter's Machete to the Skirmisher's Sabre(the red one). {U just need to clear one side jungle camps with the help from bot lane}

After u upgrade to the Skirmisher's Sabre, u will reach lv 3 and 0 gold in pocket. Then go clear the other side of jungle or gank if u start the red side.

WARNING: only gank if u have both smite(use it on champion) and red buff. OR JUST FARM UR JUNGLE. Since AD Fizz does not do any dmg then just lv 3 or 4. At least with my AD Fizz Jungle runes and masteries(the red and the Quintessences with physic and magic penetrations), the lv 3 or 4 AD Fizz is totally trash if u dont have red buff and smite.

However, if u have both smite and red buff, and the enemy is about 50% health, u can easy solo the enemy. AND PLZ DODGE AT LEAST ONE SKILL SHOT WITH UR E PLZ.

IF U DID NOT GANK when u have red buff and smite, then try to clear the other side of jungle camps. It will make fizz to lv4 or 5.

1. at this time, if u dont have red buff anymore(start red then u dont have it after clear the other side of jungle), then try to clear the available camps on map and make to lv6. OR IF U FIND ANY ENEMY IS UNDER 30%, and U HAVE SMITE, AND HE IS ALONE(not enemy jg or sup's cc), kill the enemy for sure.

2.IF u have red buff, let ur solo lane teammate bait enemy's cc if possible. Go in fight with ur Q(NOT E PLZ), in the mid air of Q, use W AND SMITE. get the enemy super low then u can use e to chase down. However, if enemy still has 60% health after u use the qw + smite combo, dont chase anymore with e. REMEMBER, AD FIZZ DOES NOT DO DMG EARLY GAME. ALWAYS, SAVE E FOR RUN AWAY(from their jg or tower hits).

If u did not die 3 times in first 10 mins, u will reach lv6. Lv6 gank is the key for the whole game for AD Fizz.

THE LV6 GANK, just make sure u have smite, then just go kill someone. The ult will do 200 magic dmg, and all ur dmg is increased by 20% for 6 secs!

THE COMBO:
GO in with Fizz's Q(NO E PLZ), in the mid air, use w + smite + ult. PLZ PRACTICE fizz's QR combo. LEARN TO USE ULT IN HALF WAY OF Q, IT INCREASES UR CHANCE TO LAND ULT. When u land the q + r + w + smite combo, do one auto if possible, then PLZ TRY TO DODGE THE enemy's CC or AT LEAST ONE DMG SKILL SHOT. Also use the Trickster to slow enemy. IF THE ENEMY DOES NOT HAVE CC, THEN TRY NOT TO USE E. Use E to chase him if he flashed or dashed away from u.

THE FULL DMG:
ULT + Q + Smite's true dot + W's dot + E + 3 to 4 autos

IF u get the kill and made enough for the Devourer, congrats, u get great chance to carry with AD Fizz jungle. IF u didnt get anything from this gank(it means u didnt help ur team, and the whole team is falling behind already), then try to farm up and build off-tank fizz PLZ(NO MORE Devourer, go tank jungle item and one triforce for dmg, rest items plz go all tank and cdr).

Even if u get the Devourer for Fizz, it is still not yet for fizz to carry the game. At this time, AD Fizz is super weak if u dont have ult and smite. DONT TRY TO SOLO ANYONE INCLUDE ENEMY SUP IF THEY ARE FULL HEALTH PLZ.

When u get the Devourer, farm up the jungle camps first, and DONT FORGET TO CLEAR THE SCUTTLERS(+2 STACKS). And get the DRAGON TIMER PLZ, u will need the five stacks from it.

Gank when u have ult and smite, try to help ur teammates and take more turrets(TURRETS>CHAMPIONS KILLS).

Tri-force first or BORK first?
If u need more burst dmg than dot, go tri-force
If u need more sustain than dmg, go Bilgewater Cutlass
IF U ARE FALLING BEHIND, GET THE SHEEN AND PHAGE FIRST(SHEEN>PHAGE)

After u build sheen and phage, then u can solo lv11 champions with about 1300 health, around 15mins, if he is not super fed.

REMEMBER, DODGE THE CC SKILL SHOTS AND TRY TO SAVE UR E FOR THE CC PLZ. OR DODGE THE BURST DMG WITH E. DONT EVER START UR COMBO WITH E, IT HAS CRAZY CD CAUSE U MAX THE W FIRST.

1. Fight for dragons for stacks!
2. Get to the Sated Devourer ASAP
3. Get 1 defense item

When to get the defense item?
1. enemy team has super burst
2. ur team falls behind

Why I'm ahead and I still build defense item?
1. AD Fizz NO BURST, u kill enemy slowly, so u live longer u deal more dmg
2. Defense item DOES NOT mean that u get the Sun fire or spirit visage, just items that give u a little bit mr or armor or health. Then u will survive the burst from syndra zed and riven.

FOR AP BURST:
Build the item with both mr and health will be the best: Spectre's Cowl.
Or mr and dmg: Hexdrinker.
Health: giant's belt

FOR AD BURST:
ARMOR: 2 cloth armor(PLZ NOT Chain Vest PLZ) since u wont need sun fire for sure
Health: giant's belt
ARMOR AND HEALTH: Ruby Crystal AND 1 cloth armor

BUILD ALL THE DMG ITEM LISTED ABOVE
then, kill the carry with 1 full combo.
DONT DIE TOO FAST, get more hits when u still alive.

AND WHY Ravenous Hydra and Hextech Gunblade?
1. Sated Devourer proc the Hydra
2. Hextech Gunblade's passive will be almost 10 secs cd, since the on-hit and auto reduce the cd by 3secs. SO U CAN USE Hextech Gunblade EVERY TEAM FIGHT 3 TIMES IF U CAN SURVIVE SUPER LONG.