Removing "Unique" from all item passives and actives
URF and One For All are memorable gamemodes for all the crazy things you can pull off. 5v5's of yasuo's were hilarious when everyone just leapt into the air. Full AP football star Malphite is just crazy in URF. Even AP Jarvan or AP Aatrox worked in URF. Imagine being able to buy 6 boots and have 700 ms. Or 5 bloodthirsters and just having nonstop heal. 2 ROA and 3 Archangels staff on Kassadin for the insane amounts of AP. 3 Runaans on anyone because AOE ADCs. Getting crushed by a Rengar? Get 2 Zhonya's and 3 Sunfires. Untargetable free damage over time. Will nearly everything be broken? Yes, but its the same way in urf. 4 WOTA's on a lux is just how this gamemode would roll, just like how URF has AP Lucian and One For All the team of Cassiopeias. I would love to see this in the new weekly gamemodes since it would change the pace. If any of you can think of a crazy build on any champ, post the items and the champs in the comments. My contribution is the DOT DOT DOT.
Malzahar or Cassiopeia :

This kind of build would be insane to play and a gamemode full of metamancing magic would be fun. If you think this kind of hooliganry would work in League of Legends, share this with others.
EDIT: I've been thinking up some builds over the past day and I got some new insanity right here
The POP
:

LAW (leaping anti-tank women)
or
:

No
:
(for 40% cdr)

!
x6
x6
x6
x5
x6
6x
x5 
x6
x6
:
x6
or
:
x3
x2
because Illaoi wasn't hard enough to kill and Corki didn't deal enough damage with each hit