And I'll play them to the best of my ability Rules: The builds have to at least be somewhat viable, no full mana katarina or anything, and I don't own all the champions, so I can't do all the builds. if anyone wants to watch, I'll be streaming on twitch.tv/akenero2 if anyone wants to join in on the fun :)
Crackhead Kalista
If you can control her with that much attack speed, you'll have some fun.
Aatrox
ADC 
and support 
are two of my personal favorites.
For Sion, max order Q W E. Build lethality (I recommend rushing Youmuu's into Duskblade or EoN). Your Q matches and even out-ranged most ADC's, so save it for trading. You should be able to all-in fairly early and turn it into a kill lane. Whether or not you win is heavily a support matchup, as Cait and Twitch are the only ADC's that really can out-damage you in lane. Level 6 you should all-in.
Support Ori start coin and other build support items. Mikael is a good one to rush. Max order E W Q. Use Q for vision control, W for utility, and E for trades. You should only really be hitting enemy champions with your auto attack early game because you're insanely mana hungry, and it's difficult to be both offensive AND defensive with the ball. This is why you get coin instead of spellthief. That said, your shield is arguably better than Janna's and your W means you can easily control engages and disengages. You can't really solo carry though because no AP means no damage. Recommend you duo this with someone competent.
AquaDragon actually has a bunch of off-meta builds on Mobafire. The Ori build is his. I also love his Tank Karthus.
Brand Jungle Maokai Support
and for actual builds.
Assassin 
and whatever boots you want
AP 
mid
AP 
and whatever boots you want
Shockwave Hecarim is the most fun build I've ever used:
Build in this order:
/ (build both, the order is up to you)
or 
Boots are up to you, Enchantment should be warrior.
I legit made an Ashe rage quit with this build.
It works with your E, which has an extended Auto Attack Range tied to it. Combine this with RapidFire Cannon and you have about 450 Range on your E auto attack. Then you just let your items do the work. You will have 3 different % mov speed items, so you will be fast as fuck and get some nice AD, you will have a crap load of On Hit Damage with RFC+TriForce+StatikShiv and will be packing quite a punch, enough to one shot squishies.
ap tryndamere
Magic Attack Speed Ivern
Crit Nunu
One fun one I'd reccomend is Mid-Kench if you can have the right matchup. Typically I play him into zed/yasuo/ekko, start doran's blade with enough runes to give 75AD starting, go flash/ignite and snowball hard off them. Build-wise, I'll usually go either sunfire/vissy first item (depending on the mid matchup) then rush sterak's 2nd as it's probably the most obnoxious thing on tahm, rounding it out with frozen hammer + tank items. Oh, and going attack speed boots is always a good thing as the 3s potential stun you can get with them can get a ton of free kills.
Tank kassadin with a manamune top. Build is sunfire, iceborn, manamune, merc treads or ninja tabi, then banshee's or ga or titanic hydra. Also, you can swap iceborn for triforce if they are really ap heavy. Take grasp or fervor.
Full AP Jinx 
On hit Lulu ADC(?) / JG
Smite / Ghost
AP lucian
AS lulu
AP Aatrox
AD Soraka
Look up Yorick.Mori on instagram. you will not be disappointed
The purple lulu builds -
AD/AS for your killer instinct ...
or the dank tank splitpush build.
Squash this fucker. 
In no particular order.
Tanky Master Yi
: Rush for 
and
, Then Proceed to have a full build of 
, , selling the revolver later on to start building Deathcap.
It's fun to play because when you use Q, the empowered auto attack after it can crit, so with a hybrid crit/AP build you can hit for upwards of 2k with your Q Beam auto attack.
The Sheen/Revolver start really shines against people like 
and
in lane. They cant farm without getting 1/2 hit by your Qs.
Braum:
Tank 
support
/
tilt the enemy carry with your base damage and make teams chase as you are too tanky to kill
You want builds? I GOT BUILDS!
-
- 
looks at own match history
I've done a lot of weird stuff in custom games, but the two most bizarre things I've done recently are:
with 
(regrettably I never even finished the hydra before losing)
with 
Also, note that I played both of these against a single heavy AD champion on the enemy team, so tweak to include MR if you wish.
Something a bit more distant in the past is Crit Trundle. Just take a Sivir build or whatever and slap it on Trundle. You have every reason to build him full AD aside from the fact that he's immobile and melee and really suffers if not built at least somewhat tanky: free AD, free attack speed, built-in armor shred...
Syndra
Manamune, Archangel, Morello, boots, dcap, void staff
Rush tear > morello > needless rod > finish manamune > archangel > rabadons > voidstaff
Oneshot ppl with ult
Full tank, Full 100% certain stats like attack speed, hp, armor, or movement speed on a champion like Zilean. I mess around a bunch with on-hit.
Something really fun is Crit chance douchebag Yi.
Atk speed/AD Reds Armor Yellows 3x Scaling, 6x scaling CDR Blues 3x MS Quints
Start Machete+Refillable Flask
Only farm. Screw ganks, they don't deserve help from the great Yi.
Rush Bloodrazor with whatever enchant you need; for instance, the warding one to counterjg or stop counterjgling
Don't get tier 2 boots, just get tier 1 boots to help with clear speed.
Bloodrazor -> Essence Reaver -> Stattik Shyv -> Infinite Edge ->Flex(Mortal Reminder, Sterak's, Deadman's Zzrot, Frozen Mallet, Randuins, Death's Dance etc.) -> Sell Blood Razor for Phantom Dancer -> Flex spot ->Flask.
Don't gank, farm, kill anything late but be careful. Spam Ctrl+3 whenever you can.
This isn't my build, but from an outdated guide in mobafire. It's fun though
Full attack speed
Lobster 
