Luden's Echo & Katarina
Katarina is a pretty strong champion (as some of you would be very willing to admit) so I figured, what'd happen if you put Luden's Echo in her build? Here were some of the results *note that this is a Katarina build of my own:
Luden's Echo (120 AP + 7% Movement Speed + Statikk Shiv-like passive) Liandry's Torment (50 AP + 300 Health + 15 Magic Penetration + Damage over time from passive) Rabadon's Deathcap (120 AP + 30% AP increase from passive) Zhonya's Hourglass (120 AP + 50 armor) Sorcerer's Shoes (any enchantment) (15 Magic Penetration + 45 movement speed) Rylai's Crystal Scepter (100 AP + 400 Health)
Now, with the addition of Luden's Echo, the passive (think of it like a Statikk Shiv for mages) works with any ability. This means that Katarina's Q (which already bounces) does bonus magic damage, to multiple targets.
Basically, at full build Katarina in Patch 5.5, you can Bouncing Blades into a crowd of targets, deal literally 2x the amount of damage Bouncing Blades would do normally to all of them, Shunpo in, and Sinister Steel them, and if that's not enough, why not throw in an extra ult or two?
This build = OP.
im sorry to the community, hate me all you like but honestly Luden's Echo is OP plz no report
EDIT: people hated my idea of building Katarina so I changed it around a bit to receive a lot less flame