Viper is picked in 5.8% of Very High matches, 6.9% of High and 9.8% of Normal, and wins 49.3% / 48.3% / 47.8%. Poison Attack slows enemies and lowers their magic resistance, Nethertoxin damages and slows the attack speed of enemies in an area, Corrosive Skin damages and slows anyone who hurts him, Predator adds damage against wounded heroes, and Viper Strike slows a target and disables its passives. He is an early-game hero: his team gains more XP in 60.3% of games before minute 15, and he wins 54.3% of games under 25 minutes, 48.6% at 25–50 and 46% past 50.
Countered by Chaos KnightViper wins the lane: Chaos Knight's team gains more XP in only 43.9% of games before minute 15. Chaos Bolt still stuns him for a random time, so Viper can't trade freely.
Viper has no escape, and Chaos Knight brings him to the fight. Reality Rift pulls Viper and Chaos Knight together and lowers Viper's armor, and Chaos Strike crits with lifesteal through the damage of Corrosive Skin. Phantasm summons several copies that deal full damage, so a single Viper Strike covers only one of them, and the copies keep their Chaos Strike crits even when the real Chaos Knight's passive is disabled. Chaos Knight's team gains more XP in 56.1% of games between minutes 15 and 35.
Chaos Knight's team gains more XP in 54.9% of games after minute 35. He wins 59.5% of 25–50 minute games (2,972 games) and 54.8% past 50 (728 games). The counter is steady in every bracket: +11.71 in Very High, +11.59 in High and +10.09 in Normal, mostly from Normal games (2,724). Chaos Knight wins 57.3% / 58.1% / 58.8% (Very High / High / Normal) against Viper, against his usual 50.7% / 50.6% / 51.5%.
Best teammate: ClockwerkThe pair wins the lane: their team gains more XP in 58.2% of games before minute 15. Power Cogs trap an enemy laner next to Viper, who stacks Poison Attack until the cogs fall, and Battery Assault keeps interrupting it.
Hookshot stuns the first target it hits and pulls Clockwerk onto it, and the cogs keep that hero inside Nethertoxin, whose damage grows the longer it stays. Predator finishes the trapped hero as its health drops, and Rocket Flare gives vision and a slow on the heroes who try to run. Their XP-gain share slips to 48.4% between minutes 15 and 35.
This is an early pairing: they win 58.1% of the 43 games under 25 minutes, 50.8% at 25–50 (1,529 games) and 46.3% past 50 (451 games), with an XP-gain share of 44.2% after minute 35. The advantage is steady: +7.85 in Very High, +9.75 in High and +7.63 in Normal. The pair wins 50.9% / 50.7% / 49.1% (Very High / High / Normal), with Clockwerk normally at only 47.7% / 47.6% / 47.4%.
Based on 2,082,000 public ranked matches of patch 7.41, played 11–25 October 2026. Advantage is the win-rate difference from what the two heroes' own win rates predict, times two (+6 is about 3 win-rate points), weighted over the skill brackets. The live numbers on the Viper page update every few hours. More guides: Dota 2 counter guides.
