For defensive masteries I take 23 points with 2 extra points dipping into Sorcery. Any Mastery that gives attack damage attack speed increased crit-chance and armor piercing are all beneficial to Varus. the one extra point in Butcher could easily be moved to Summoners Wrath if you prefer more offensive summoner spells.

4 points in defense for increased Heal and Resistance making you last longer early game.

3 points here to Expanded Mind I have found mid game Varus burns through mana quickly, this helps alleviate this

I Feel almost all spells are viable for this Champion with a few exceptions, it all just depends on how you wish to play him. I prefer spells that help you stay in lane early game such as Heal and Teleport. Getting a good start to a match seems to be a key to Varus. Pulling him back from a poor early game has been hard for me.

There are a few that I would recommend against.

• Clarity
• Surge
• Smite
• Revive
  
  Clarity would be more suited to a support Champion, this build is based on doing most of its damage through auto attacks and has addressed insufficient mana problems.
  Surge While the attack speed would be nice the increased AP would only be useful to [Chain of corruption], and scales poorly with [blighted quiver]
  Smite Leave this for the jungler you shouldn't even need to kill health mobs with the amount of life steal you have with this build.
  Revive The cooldown is way to long to be as useful.

You only have 3 activated abilities, meaning you have less to worry about, But the cooldown for those feels very long considering how often you Auto attack.
I put one point in each ability for the first 3 levels and then level Piercing Arrow and Blighted Quiver back and forth getting levels in Chain of Corruption as soon as they are available. I max Hail of Arrows last.

This skill shot is a bit different as it is a charged shot but can be released early. It gains dammage and distance as it chareges and you can move slowly while chargeing, but moving while charging is not the easiest thing to get the hang of. It will pass though all enemies damaging them pregreessively less as you hit more enemies so you might as well just shoot through the minions and enemies rather than shimmying to the side to get that extrta damage, in my experiance while you are moving into position the enemyy is usually getting away. I get Piercing arrow first and max it alongside Blighted Quiver.

This is a great passive ability, giving extra initial damage up to 3 times and bonus damage if you strike the enemy with an activated ability they are damaged more for each blight point they have. Maxing it second alongside Piercing Arrow makes your auto attacks that much deadlier. The blight points only stay for 6 seconds but if you miss the chance to trigger them dont fret too much as you can apply more for free rather quickly. This is great for picking up Minion kills early game, as well as good harassment.

Your Second Activated ability, this is more utility than a real damage dealer. It places an AOE, causeing arrows to rain down dammageing anyone in the area, and then blights the ground for a few seconds slowing anyone in or moving into the area. Great for placing behind the enemy causing them to rethink their retreat or slow them long enough to pick up the kill. remember that the arrows will hang in the air so if you want to land it on a moving enemy then you will need to learn to lead them a bit. It seems to hang in the air the same amount of time no matter how far you are shooting the arrows, making it a very fast attack. Get one point at lvl 3 and 1 more point at lvl 10 then max it last.

Your Ultimate and last activated ability, It greatly damages the primary target and immobilizes them. It can then jump to additional champions, damaging and immobilizing each enemy champion in range once. This is great for several uses. Locking an enemy in place for your team or yourself to finish off, or if you are lucky, laying a large amount of damage to the enemy in a team fight. Don't be afraid to use it on a single enemy if you think they will get away, but do try to save it for team fights if you can. Hitting teams with this is fun and powerful but doesn't always work, people are quick to jump away from their allies if they are infected. But even if it doesn't jump to more champions here it is still useful, causing the enemy to blow its flashes to avoid the effect is a good consolation prize. It is also important to note the effect continues after you die so if you are going down locking your killer down to save your team mates is worth the use.

With these Runes You will have High Early game Survivalbility, making Soloing Mid or Top Easyer, Though Varus Benefits wonderfully froim good Support on Bot Lane as well. Early Game I concentrate on Harrassment and Minion Kills Only aiming to Drive my opponenet back to base or to use up their Potions to Heal. I donb go for Kills playing aggressive with auto attacks but defensice by not chasing or Tower diving. But If the oprortunity presents itself for an unrisky kill than by all means take the Shot. (no pun intended) Coincentrating on Minion kills will keep your attack speed high as well as generate the gold you will need for your Bloodthirster. If you are solo, Expect your tower to go down last wonce your team starts to group up for Mid game.

By now you should know how hard the Opposition is hitting, and you have a decision to make, Keep in lane for a bit more gold or group up. Being a Glass cannon you will want to stick to your team. if you are cought alone by one or more enemies then you are as good as toast if your ailities are on cooldown. In team fights you will want to hang in the back dont let anyone get in your face, slowing and immobilizing letting your allies take most the hits and letting your auto attacks replenish your health. Keep taking out minions if you dont have any enemies nearby, but you wont have to worry about waiting for last hits you should be able to kill them without worrying about your own minions picking them up. This will keep your health up and gold in your pockets. If you have the chance to can solo dragon at around lvl 11 but be weary of Sight wards. If they know you are there alone they will come and kill you.

You might not get to the end of this build by the time you have pushed into the enemy base. But this is prretty much the same as Mid game, stick with your team and stay back away from the enemy champions and dont let an over Zealous melee teammate over commiting kill you too.

In team fights there are a few things you should do no matter what.

• Use Hail of Arrows to slow the enemy down or cut off their retreat.
• even if it wont hit all your opponents Chain of Corruption will stop at least one enemy and allow your team to get the kill or allow them to escape.
• attack. constantly attacking whoever your team is concentrating on. Your hits might not be heavy but they are often, and with Phantom Dancer and Infinity Edge a little over that every other shot will hit critically. this includes attacking minions to restore your health

In lane again be aware of who your allies are attacking, aid them. otherwise default to the opponent with the least amount of health or Health%. for example avoid concentrating on tanks.

Once you have some life steal remember hit those minions to replenish your health. if you have full health then your whole lane will be more intimidating.

I feel this is a thing that unfortunately is not so common, so ill touch on them.

Lock in before calling "mid" in a random group.
Try to avoid Kill Stealing
be a gracious winner, and not a sore loser
In essence "Be polite. Be efficient. Have a plan to kill everyone you meet." - the sniper