Hero Mastery

Viper

A lane oppressor: Poison Attack slows + dots, Corrosive Skin grants magic resist + a slow aura that makes you hard to kill, and Viper Strike locks a target down.

Mastery parameters

Your GPM, last hits and damage per game against other Viper players — average vs Top 20%.

Members only

Learning journey

1 Know the kit
2 Win the lane
3 Timing & rotations
4 Win the fights
5 Master

5 stages, each with one target from your own games and one short quiz. Make Viper your mastery hero to start — progress shows on Home and Arcana.

Phase by phase

The 1v1: last hits + rune control

You 70%Team 30%

Skills in lane — Pro cores max Nethertoxin (W) first — 61% of 389 games since patch 7.41, then Corrosive Skin (E). Some max Poison Attack (Q) first instead (37%). First talent at level 11.
Level 6 — Viper Strike — Viper Strike lays a heavy slow — a near-guaranteed kill. Open ganks with it on anyone trying to run.
Early lane dominance — Poison Attack + Corrosive Skin win you nearly every lane matchup. Snowball that early lead.

Skills 1–7

Starting items

Iron Branch31%
Circlet of Nobility24%
Tango14%
Faerie Fire14%
Observer Ward7%
Enchanted Mango3%

Pros buy this phase

Power Treads71%
Boots of Travel13%
Perseverance6%
Dragon Lance5%
Falcon Blade2%

The Midlaner's job this phase

Focus on last hits & denies — a 10-creep lead by minute 5 is a real level advantage.
Minutes 6, 8, 10, …: check water/power runes. A full Bottle means you can spam spells.
Ask a support to arrive 30 seconds before power runes when your lane is rough.

Counters & weaknesses

Passive-reliant hero

The items that shut Viper down, 4 heroes that trouble it, and your answer when you play it.

Members only

Why this way? How OpenAI Five learned

One hero, one role first
OpenAI's first bot played only Shadow Fiend, only mid, until it mastered it. Stay on Viper in one role before moving on.
Small, measurable rewards
OpenAI Five was rewarded for last hits and staying alive long before it understood winning. That's why each journey stage has one number to hit.
From yourself to the team
Its 'team spirit' rose over the game: early on, look after yourself; late, play for the team. Each phase's meter shows the split.
Use proven builds
OpenAI Five's builds were hand-written, not trial and error. Start from the pro build, then experiment.

Phase items: what pros buy on this hero (OpenDota). Parameters: percentiles of players on this hero (OpenDota). Item effects checked against Valve's own item data.