I have recentltly been playing Varus AD mid Caster and I think it's amazing, the guide I used is linked HERE.
The general idea is to abuse Varus's Q, Piercing Arrow, details below, by spamming the ability to poke down your opponent, the abilities excellent range and damage allow you to control your lane and force your opponent to base.
The core items are Manamune (for mana to spam Q) Ghostblade and Ionian boots for CDR (for quick spam) and Last Whisper for damage.
If you are here solely to say "that varus is terrible" please read the guide and try it, if it's your playstyle you'll find it doesn't suck.

Now, here's where my question starts, could the same logic be applied to Kalista? Her Q (Pierce, featured below) is quite similar to Varus's although it lacks the range, but that isn't the only reason I've come up with this.
Kalistas sentinels provide an excellent way to keep and eye out for potential river ganks.
Kalista can Oathsworn Top Lane for late game fight initiations with her R or she could Oathsworn the Jungler for Deadly ganks on mid almost guranteeing a kill every time your jungler visits mid.

This does mean relying on just Kalistas Q and E for most of the early game but they are the only 2 abilities you really need with Kalista, prioritising boots after Muramana not only lets you reduce the cool down of Q quickly but also allows your passive to jump further meaning you can dodge the skill shots common in mid lane.
Finishing the build with a blade of the ruined king or even a trinity force (why not both) could leave Kalista capable of bursting down one target in 4-5 hits.

Any thoughts on the idea would be great, nor looking to create a new meta, just a noob with an idea :D


Piercing Arrow
Varus starts drawing back his next shot, gradually increasing its range and damage, then he fires it, dealing minimum 10 / 47 / 83 / 120 / 157 (+1.0 per attack damage) to maximum 15 / 70 / 125 / 180 / 235 (+1.6 per attack damage) physical damage, reduced by 15% per enemy hit (minimum 33%).

While preparing to shoot, Varus cannot autoattack or use abilities, and his movement speed is slowed by 20%. After 4 seconds, Piercing Arrow fails but refunds half its mana cost.



Pierce
Kalista hurls a fast and narrow spear, dealing 10 / 70 / 130 / 190 / 250 (+1.0 per attack damage) physical damage to the first enemy struck.

If Pierce scores a kill, the spear will continue onward, passing all Rend stacks from the dead victim to the next enemy it hits.