Wit's isn't bad, there just isn't anything to support it

The thing is a dead-end item. Unlike BotRK, its onhit damage doesn't scale at all and it lacks the all-important ranged slow to help champions stick. So why not create some companion items for it to stack with? If there were several of these things, all granting IAS and OnHit magic damage, they would stack really nicely with each other. We'll start with a core item and then expand from there.

+ = Ionic Spark Grants IAS, HP, and 75 magic damage on every third attack. bzzzZAP!

Spark is now the core item for a range of nasty Bruiser-focused toys, each designed to synergize with each other. All of these items retain Spark's 'three hits and proc' effect, since Riot seems to love that stuff now. We'll start with the subject of our topic.

Wit's End now builds out of Spark, a Negatron Cloak, and a Dagger. The thing whomps the target for 120ish magic damage on its proc, but more importantly its MR stealing properties are now tied to your bonus Magic Resist. This provides the larger, more expensive Wit's a much needed source of scaling.

Feybane builds out of Spark, Warden's Mail, and a Dagger. In addition to netting some more OnHit magic damage, its Cold Steel passive now steals base attack speed from targets hitting and/or being hit by the wielder. Only the highest source of IAS gain would be counted.

Madred's Bloodrazor makes a triumphant return, building out of Spark, Crystalline Bracer, and a Dagger. Things are a bit inverted this time, however. Bloodrazor now deals bonus magic damage OnHit equal to 12% of the wielder's max HP rather than the target's on the third-hit proc. Hitting an enemy champions and large/epic monsters with this ability triggers a regeneration effect that heals the user for (percentage) of their max HP over five seconds.

Graviton Flail is it a wave? Is a particle? Is it slowing enemy champions? Builds out of Spark, Giant's Belt, and a Dagger. This thing deals magic damage every third hit and applies the Gravity debuff to the target. Enemies smote with Gravity are slowed while you and your allies gain a small speed buff when moving toward them.

Which ones look good? Which ones look awful?