If it was a league item.
Pick any item, weapon, or "armor" from any game and give it league stats. (its okay if its over powered but try to be a little reasonable)
For example
Master Sword (Zelda)
cost - 5500 gold
build path 
+ 
+ 
60 AD 70 AP 300 mana
100% Crit chance on undead champions
Unique passive - 15 magic pen
Unique passive - Not dealing damage for 5 seconds charges a beam of light granting 400 range for your next auto attack. Charged auto attacks scale off of both your AD and AP and do magic damage rather than physical damage. (melee champions only)
edit: Don't feel restricted to items that haven't been said already. feel free to give your own takes on items that have already been said.
+ 
+ 
+ 680 Gold.
120 Ability power
10% CDR
Unique Active -
Deals 15% of target champion's maximum health in magic damage and applies the debuff, Doom. Doom amplifies all magic damage that champion takes by 20% for 4 seconds. 90 second cooldown (750 range).
+ 
ulti)
to help with movement speed and cooldown reduction.
so yeah I would. Seriously, Liss' W and R would be so much fun to use with this thing. Although, I'm not unaware of how this could bite me in the ass considering other mages have access to it.
I'd love to see this in an RGM actually, it'd be the perfect environment and it wouldn't be a balance mess, because it's an RGM, so who cares.
Ohmwrecker
and 
) that hooks the first enemy Champion hit, deals 100 (+60% total AD) attack damage and pulls them directly in front of you (basically like Blitzcrank's hook). CD: 60 seconds.
+ 
+ 
+ 2400 + Die once.
)
