Beginner's guide to carry Viper

Introduction

This is my first guide, I'd appreciate feedback. It's also intended for beginners, so I will intentionally be quite verbose, explaining the reasoning behind my choices so that readers will be able to make their own decisions depending on the situation.

Viper is a strong mid game carry that can lane well (due to his poison orb and last hit boosting passive) and gank well (due to his strong early DPS and poison slows).

Pros:

• Great laner
• Strong mid game
• Strong ganker
• Farms well
• Ranged
• Tanky late game

• Item dependent
• No escape abilities + slow movement speed = can be ganked easily
• No stuns
• No AOE

• You need a mid game carry or a late game tank
• You need someone to dominate a lane

• You have too many farm-dependent heroes
• Your team won't be able to capitalize on a mid game advantage
• Enemy team has strong early gankers
• Enemy team has blinks/escapes

Skills

If you want the details of each skill, just hover your cursor over the icon and a pop-up will appear.

Poison Attack:

Poison Attack is Viper's orb effect. It slows for 2 seconds and does damage over time to an enemy. If you hit an enemy already under the effect of Poison Attack, the duration of slow/DoT will be reset to 2 seconds. This means that hitting an enemy with Poison Attack more than once every 2 seconds only wastes mana. I would recommend never having Poison Attack on auto-cast as the 20 mana will burn through your mediocre mana pool very quickly.

Another reason to not have Poison Attack on auto-cast is to avoid creep aggro in lane. If you manually cast Poison Attack on an enemy hero, it counts as casting a spell and the enemy creeps ignore it. If you have it on auto-cast and you right click an enemy hero, the enemy creeps recognize that you're attacking their hero and will attack you. This is one of the reasons Viper is such a strong laner, you can throw Poison Attacks at the enemy without drawing aggro.

The cooldown for Poison Attack is 4/3/0/0, which means that at level 3 it has no cooldown. Once it hits level 3 you can start chasing down enemy heroes with it (without drawing creep aggro) and you can really force the enemy out of lane or kill them. This is also when you can start ganking (although waiting for your ultimate at lvl 6 definitely helps)

Poison attack actually adds 25 to Viper's range (575->600) which is equivalent to most ranged heroes but that 25 difference is nowhere near as noticeable/useful as the slow.

Nethertoxin:
Nethertoxin is the other reason that Viper is such a strong laner, it does bonus damage the more health the unit is missing. At level 1, it does 16 extra damage to creeps (32 to heroes) missing 4/5 of their health significantly increasing your last hitting potential.

Nethertoxin is also great against weakened enemy heroes allowing you to finish them off quickly and more likely to get the killing blow if your team is also attacking them. It also works on towers. Viper's illusions also have Nethertoxin and deal more damage to injured enemy heroes, one of the reasons why Manta is such a good item on Viper, Viper's Nethertoxin combined with that of his illusions makes enemy heroes melt once they hit half health or so.

Corrosive Skin:
Corrosive Skin is what makes Viper a tank late game. It grants additional magic resistance (on top of the 25% innate magic resistance) and slows the attack and move speed of anyone that auto-attacks viper. The attack speed slow, in addition to Viper's naturally high armor, significantly reduces the damage Viper takes from auto-attacks. The movement slow, in addition to Viper's other slows means that Viper can kite almost any melee hero unless Viper is stunned (even then the 25% attack speed reduction significantly decreases incoming damage)

Viper Strike:
Viper's ultimate slows the enemy significantly (stacks with all other slows) and does a decent amount of damage over time. The slow wears off quickly, but if you're still hitting them with Poison Attack that doesn't really matter.

Use this ability to gank or in teamfights. The mana cost is not insignificant and you want to be sure that you have enough mana to cast it every time it's off cooldown (another reason to be generous but judicious with the poison attacks).

Aghanim's note: Aghanim's Scepter increases the range of Viper Strike to 800 (which is longer than the cast range of most spells and the attack range of every hero but sniper) and decreases the cooldown to 12 seconds. It's actually a decent upgrade but this build is focused on Viper's DPS so it's not recommended here.

Items

Starting items:
2 Slippers of Agility - damage/last hitting
1 Tango + 1 Healing Salve - regeneration to stay in lane longer
2 Iron Branch - cheap health, mana, and damage

Early items:
Boots of Speed - viper has one of the lowest base move speeds in the game, he desperately needs boots
Magic Wand - good stats item, provides some burst regen when needed, frees up some inventory space taken by the two iron branches

Boots:
Power Treads - the attack speed and movement speed boost are nice, the bonus health from keeping them on strength is the biggest factor. Viper has good armor and magic resistance plus the passive attack speed slow but low health. The bonus 152 health from strength treads are much needed. I would recommend keeping them on strength pretty much unless/until you get a Heart of Tarrasque.
Phase Boots - Phase boots give you more mobility and higher attack damage, great for ganking. Not as much DPS late game as power treads.

Items:
Yasha - Yasha gives Viper everything he needs to do more damage, agility and attack speed for DPS and movement speed to get more attacks in/better chasing. The components are relatively cheap and add to Viper's damage/farming ability making completing Yasha easier.
Vanguard - VAnguard gives HP, health regen, and damage block. Combined with Viper's Corrosive Skin it greatly increases his survivability. BUYING A STOUT SHIELD WHILE YOU HAVE TWO SLIPPERS OF AGILITY WILL MAKE A Poor Man's Shield WHICH YOU CAN NOT DISASSEMBLE
Manta Style - Viper would do well with just the stat bonuses of Manta, but it's the active that makes Viper a beast. Activating Manta creates two illusions of Viper (that also have Nethertoxin) confusing the enemy while doing extra damage. Manta also dispells debuffs and can avoid incoming attacks/stuns. The majority of enemy debuffs (silence, dust of appearance, battle hunger) will simply disappear when you activate Manta Style. Activating Manta when a (most) projectile stun is inbound will make that stun miss/have no effect.
Shadow Blade - The invisibility and move speed both allows Viper to gank like a boss and escape bad situation while the bonus attack damage for breaking invis is a great start to a gank. If the enemy team is organized, they will get Gem of True Sight, Dust of Appearance, or Sentry Ward eliminating most of Shadow Blade's usefulness.
Aghanim's Scepter - Increases the cast range, decreases cooldown to 12 seconds (!) and decreases the mana cost of Viper Strike, not to mention the stats and HP+MP. Allows you to spam your ultimate, use it in every gank or multiple times in a teamfight. Combine with Phase Boots to get in range easier.

Luxury:
Butterfly - Evasion makes you even tankier, adds an absurd amount of attack speed/damage. Huge DPS boost.
Heart of Tarrasque - Huge health boost as well as massive regen out of battle, never need to go back to base again and last forever in a fight. Huge Tankiness boost.
Hood of Defiance - Viper already has a large amount of magic resistance, if for some reason you're still getting rocked by magic damage, a hood will make you even more survivable
Monkey King Bar - Adds a lot of DPS and the true strike is great for pushing uphill into their base as well as against evasion heroes (or riki's cloud)
Black King Bar - Viper's magic resistance should mitigate most of the magic damage, get this for the health boost and preventing stuns/disables.
Sange and Yasha - Gives both yasha's agility and move speed and sange's slow and strength, generally outclassed by Manta but still synergizes well with Viper

ALWAYS CARRY A Town Portal Scroll (except heading out to your lane the first time)


Questions:
What happened to the two slippers of agility? Most likely sold. If you're taking a lot of harassment in lane, you can add a Stout Shield to make a Poor Man's Shield. Some people like turning them into Wraith Bands for the extra damage/stats. I'd prefer to just buy components of Yasha for extra damage/stats. You'll eventually have to sell the Wraith Bands anyhow.

How to Play

Laning:
Viper can lane anywhere. He can solo mid or side lane with a babysitter. Either way, his laning strategy is mostly the same. Get last hits and harass the enemy with Poison Attack. Last hits are more important than harassing/denying! Be wary of enemy heroes coming to gank you, as you are at your most vulnerable early game. If you're facing heavy spell/right click harassment you can get a point in corrosive skin early (still want lvl 3 Poison Attack by lvl 5 though).

Early Game:
Once you hit level 5/6 you can be more aggressive and chase the enemy heroes out of lane or kill them. At this point you can start ganking, but don't spend too much time out of lane since you're missing xp and gold for every creep wave you miss. Use TPs to get to (or from) your target lane faster, hit them with Poison Attacks/Viper Strike and chase them down until they die. Be careful about chasing them under their tower or enemy heroes coming in for a counter gank.

You have no stun, so you have no way to prevent enemies from TPing out as soon as they see you coming for them. Hopefully an ally in the lane you're ganking has a stun or way of disrupting the TP. You may also be able to kill them before they TP or they may not have/use a TP.

Mid Game:
You are at your strongest mid game (once you get Manta, Vanguard, Aghanim's). Use your advantage to push towers with your team and gank/force fights. In teamfights you want to keep their carry poisoned to prevent him from tearing through your team or escaping while you want to poison chase down weak/fleeing enemy heroes.

Late Game:
If you got some kills/towers mid game, you should be pretty farmed. Capitalize on your mid game advantage to get stronger while preventing the enemy carry from getting bigger. Determine what you need, more DPS or more tankability and get the appropriate item. You can kill Roshan fairly easily due to the attack speed slow of Poison Attack and Corrosive Skin making him seem like he's moving through molasses.

Friends and Foes

Weaknesses
Pure Damage - goes right through all of Viper's defenses and hits his low health pool hard.
Early Ganks - Viper starts with low health and move speed, making him susceptible to early ganks. Without levels/items, he's not much of a threat in mid or late game.
Magic Immunity - negates all of Viper's slows (note: if you Viper Strike someone who is magic immune, they will still be slowed but take no damage; if you Viper Strike someone then they become magic immune, they will take neither be slowed nor take damage)

Foes

• Pudge: The pure damage from his Meat Hook combined with the slow from his Rot means you aren't getting away if he hooks you early
• Omniknight: His repel prevents your slows from having an effect
• Doom Bringer: Doom counters everyone, his ult disables abilities and items (Manta)
• Outworld Destroyer: Viper doesn't have the highest intelligence gain, so OD's Sanity's Eclipse will hurt while his Arcane Orb does a significant amount of pure damage. Luckily he's squishy, so it will be a short intense battle that you just might win.
• Silencer: Silencer's Curse of the Silent is only dispelled by Viper Strike, so it will do a significant amount of damage every time he casts it. His Glaives of Wisdom do pure damage. He can silence you preventing your slows from working.
• Enchantress: Her Impetus does a significant amount of pure damage from outside of your attack range. She has a strong slow and slows attack speed of those attacking her.
• Tinker: Laser does pure damage and makes you miss. He always has Boots of Travel ready to teleport away.
• Lycanthrope: Lycan's Shapeshift gives him max move speed, meaning your poisons will not slow him at all. If you let him get farmed ( Skull Basher) he can chase you down late game. However, you have the advantage early game and you can gank him while he's jungling (before he has his ult or when it has a long cooldown).

• Venomancer: Laning with Venomancer is almost unfair. His Poison Sting and Venomous Gale combined with Viper's Poison Attack results in a kill almost every time.
• Axe: Battle Hunger does a lot of damage unless the target gets a kill. Viper specializes in chasing heroes out of lane. They are forced to flee and take BH damage, or stay and die to Viper.
• Everyone: I can't really think of a teammate that Viper doesn't have some sort of good synergy with. Then again, I really like Viper so I'm biased.