So, with the reveal of Kayn and Rhaast, it is all but confirmed that the corruption taking over Varus is in fact a Darkin. A lot of people seemed surprised at this, despite the fact that it was a popular fan theory. Why? Because Varus doesn't feel like a Darkin. His lore, visuals, and even gameplay are missing the things that make Aatrox and Kayn/Rhaast feel similar. I thought I would present my thoughts on how a VGU for Varus might change that.
The big problem with Varus's lore is simple: The word "Darkin" does not appear anywhere in it. What we need is a name and personality for the Darkin taking over Varus's body, and some form of interaction between them. Varus is a bit further along the course of his corruption than Kayn is, and the different dynamic would be interesting to see. Kayn is still able to fight Rhaast, but Varus knows he has already lost his battle. I wouldn't want the new Darkin to take too much focus from Varus, though. A good way to accomplish this would be through its personality. The new Darkin would be more reserved than Rhaast is, sort of a [Blue Oni to Rhaast's Red](http://tvtropes.org/pmwiki/pmwiki.php/Main/RedOniBlueOni) (TvTropes warning), and less talkative than him or Aatrox. The main trait I would want to see would be that instead of fighting, Varus and the Darkin realize that the Darkin has already won and Varus has accepted that.
Varus would need new lines to interact with his Darkin counterpart, and is in dire need of a VO update anyway. He only has about 25 lines, while more recent champions have many times that number. As I said earlier, I don't think Varus's Darkin would be as talkative as Rhaast. It would have enough lines for the player to be aware of its presence, and it would interact with a few other champions, but it would leave most of the talking to Varus. I think good places to insert conversations between Varus and the Darkin would be "first move" lines, some item interactions (Like Corrupting Potion), and special taunts/jokes for Aatrox, Kayn, and Rhaast.
Varus's model and animations don't really fit the Darkin theme. Darkin are black and dark red, while Varus is purple, white, and bright red (his Q and his scarf). I would add some dark red to the more corrupted areas, particularly his bow, and make his animations fit the Darkin color scheme a bit better. The shape of his bow is also off. Darkin weapons, looking at Aatrox and Rhaast, are spiky and angular, while in game Varus's bow appears mostly as a smooth curve. I would want it to resemble Aatrox's sword more, particularly since it already expands and retracts in a similar way. This would give players a visual signal that yes, this weapon is a Darkin.
Varus has an OK kit, but it could do with some improvement. His passive is frankly kind of boring and does not provide much help when behind, and besides his ult, his other abilities are kind of bland. My goal with any kit changes would be to make his kit more interesting and to make him feel more like a Darkin champion. I would want to keep the changes relatively small, though, to avoid alienating current Varus mains and to minimize the necessary adjustment.
First, we should look at what Varus does now. His Q is a strong poke ability, his ult provides CC and playmaking opportunities, his passive and W reward attack speed, and his E provides utility and a bit of weak self-peel. In particular, his W rewards mixing attacks and ability casts, so that should be the focus of any kit intended to feel like Varus.
Second, we should look at what Aatrox and Rhaast have in common, since those are the traits that will make a champion feel like a Darkin. I particularly notice one major similarity: both have mechanics that allow them to regain health through their attacks. Aatrox has his passive and W, and Rhaast has his passive and ult. Particularly importantly, Kayn does not have the healing abilities, meaning that they are only connected to Rhaast. Therefore, Darkin need to have a way to heal based on combat.
With those points in mind, here is my idea for an updated kit for Varus:
(A quick note: I did not include exact numbers, because if I did they would be horribly unbalanced. I'll leave that to the professionals.)
##Passive: Blighted Quiver
Varus's autoattacks do additional magic damage (scaling with level) and apply Blight, stacking up to three times. Varus's abilities consume Blight stacks on their targets to do %HP magic damage (scaling with level and possibly AD or AP) and apply additional effects.
Explanation: Varus's current passive is boring, difficult to even notice, and does almost nothing for him if he is playing from behind. His W is a passive skill that interacts with his abilities, but it takes up a slot that could be used for more of those interactions. I solved both problems at once by putting his W in his passive slot. And honestly, it does make a lot more sense there.
##Q: Piercing Arrow
Varus charges a powerful shot that gains increased damage and range the longer it is charged. Does physical damage with high AD scaling. **Blight:** Refunds part of the mana cost based on the number of Blight stacks consumed. No matter how many targets the arrow hits, it cannot restore more than a certain amount of mana (less than the original cost).
Explanation: Varus's Q is his core ability. While it would need some numbers tuning, I believe it should remain largely unchanged. The mana refund allows him to turn a good trade into a great one if he can get a few autoattacks in on a careless opponent.
##W: Focused Retribution
Varus's next four attacks gain a large amount of attack speed and heal Varus slightly based on his missing health. **Blight:** If the target of the fourth attack is affected by Blight, the attack consumes the stacks to do a large amount of additional physical damage and increase its healing for each stack. If stacks are consumed this way, the fourth attack does not apply Blight.
Explanation: This ability fills his W slot now that it has become his passive. It provides the healing expected from a Darkin and gives Varus a way to stack Blight quickly, although he will need to choose whether to use the stacks for attack number four or for something else.
##E: Hail of Arrows
Varus fires several arrows at a target area, doing physical damage based on AD and leaving behind a slowing zone on the ground. **Blight:** Champions affected by Blight that take damage from this ability are afflicted by Grievous Wounds and slowed more. Additionally, the slow persists after they leave the zone for a duration based on the number of Blight stacks consumed.
Explanation: Varus's E is his only (non-ultimate) method of self-peel. I figured that its blight interaction could simply make it better self-peel. Additionally, I wanted to force him to be in combat already in order to apply Grievous Wounds.
##R: Chains of Corruption
Varus fires an arrow surrounded by tendrils of corruption, doing magic damage based on AP and immobilizing the first enemy champion hit. Then, the corruption spreads to nearby champions until all nearby enemy champions have been affected. **Blight:** The corruption spreads farther based on the number of Blight stacks on the target. In addition, a full three Blight stacks are reapplied after the target's stacks are consumed.
Explanation: Varus's ult is well-designed already, so all I added was an interaction with Blight.
And there you have it! My ideas for a Varus VGU. Constructive feedback is encouraged! I'd love to hear what people have to say about it, and to improve my design skills.