Scan Ability Guide
Master Scan timing and detection strategies for competitive advantage
Understanding Scan Ability
Scan Cooldown
4.5 minutes (270 seconds)
Scan is a shared team cooldown ability. Once used by any player on your team, all team members must wait 4.5 minutes before it can be used again. This makes coordination essential to avoid wasting this valuable detection tool.
Scan is a powerful team-wide ability that reveals enemy units in a targeted area. Available to all players, it provides crucial map information without risking hero lives. Understanding when and how to use Scan effectively can be the difference between winning and losing important fights.
Scan Mechanics
Duration
8 seconds
Scan reveals enemy units for a full 8 seconds, giving you plenty of time to assess the situation and make decisions.
Detection Radius
900 units
The scan area covers a 900-unit radius from the targeted point, revealing all enemy units within range.
Cooldown Type
Shared Team
All five team members share the same cooldown. Coordinate before scanning to maximize value.
Detection Method
True Sight
Scan detects invisible units, smoked units, and units in fog of war. It provides complete vision in the area.
Critical Limitation: Roshan Pit
Scan does NOT detect units inside the Roshan pit itself. When checking for Roshan attempts, scan the entrances to the pit or the area immediately outside, not the pit interior.
When to Use Scan
1. Roshan Detection
One of the most valuable uses of Scan is detecting enemy Roshan attempts:
- Scan the entrances: Target the areas just outside the Roshan pit entrances, not inside the pit itself
- Timing is key: Use Scan when you hear Roshan being attacked or suspect the enemy team is missing
- Follow up quickly: If Scan detects enemies, your team must move immediately to contest or you've wasted the cooldown
- Strategic zones: Scan common Roshan setup positions near the pit entrances for the most information
2. Smoke Gank Detection
Scan can save your team from deadly smoke ganks:
- Missing enemies: When multiple enemies disappear from map, scan common smoke paths toward your lanes
- Jungle choke points: Scan narrow jungle paths where smoke ganks typically travel
- High ground areas: Check cliffs and trees where smoked enemies might be waiting
- Pre-fight positioning: Before major objectives, scan the area to detect hidden enemies
3. Split Push Detection
Use Scan to track enemy split pushers and ratters:
- Creep wave mystery: When waves push without visible enemies, scan the area to find invisible or hiding heroes
- Lane pressure: Detect heroes like Nature's Prophet, Tinker, or Furion pushing lanes without vision
- Base defense: Scan behind towers or in trees to find heroes attempting backdoor attacks
- Track movements: If a split pusher disappears, scan their likely rotation path
4. Objective Control
Secure objectives by scanning suspicious areas:
- Before pushing high ground: Scan behind enemy towers and in trees to detect ambush setups
- Ancient stacks: Check if enemies are taking your stacked camps without vision
- Rune control: At critical timing (especially night time), scan rune spots to detect invisible enemies
- Shrine areas: Scan around shrines when enemies might be healing but out of vision
5. Team Fight Preparation
Gain a strategic advantage before engagements:
- Fog positioning: Before initiating, scan the fog to see if additional enemies are nearby
- Counter-initiation: Check trees and cliffs for enemies waiting to counter-initiate
- Escape route check: When retreating, scan potential escape paths to avoid running into enemies
- Blink dagger detection: Find heroes with blink daggers hiding in fog waiting to initiate
Reading Scan Information
Understanding Scan Results
When Scan detects enemies, red circles appear over their locations. Here's how to interpret the information:
Positive Scan (Enemies Detected)
- Count the dots: Each red circle represents one detected unit (heroes or creeps)
- Movement patterns: Watch how the circles move to understand enemy intentions
- Clustered vs scattered: Grouped circles indicate a team, scattered ones might be farming
- Hero identification: Combine with missing enemy heroes to deduce who is where
Negative Scan (No Detection)
- Area clear: The scanned area is safe for the next few seconds
- Redirect focus: Look at other areas of the map for enemy locations
- Timing info: Enemies were there earlier or are moving away
- Still valuable: Negative information is better than no information
Advanced Scan Reading Tips
- Distinguish heroes from creeps: Fast-moving circles are likely heroes, slower ones might be neutral creeps
- Duration awareness: The 8-second reveal gives you time to plan or reposition
- Immediate action: Don't waste time analyzing - make quick decisions based on detected information
- Combine with map info: Cross-reference scan results with minimap and hero positions
Communication with Team
Before Scanning
Always announce before scanning:
- "Scanning Roshan pit" - Let team know you're checking for Rosh
- "Scanning for smoke" - Alert team you're looking for ganks
- "Save scan for Rosh" - Prevent teammates from wasting it
- "Scan on cooldown for X minutes" - Keep team informed of availability
After Scanning
Immediately share results:
- "3 heroes at Rosh entrance" - Be specific about what you found
- "Negative scan, area clear" - Even empty scans provide information
- "They're doing Rosh, move now!" - Call for immediate action when needed
- "Smoked gank incoming mid" - Warn teammates of danger
- "Scan CD: 3 minutes" - Let team know when it's available again
Coordination Best Practices
- Ask before using: In voice chat, confirm with team before using scan on anything non-urgent
- Priority targets: Agree with team on high-priority scan targets (Roshan > Smoke > Split push)
- Cooldown tracking: One player should track and announce when scan is available again
- Ping + voice: Combine ping location with voice communication for clarity
- Quick decisions: Once scan reveals enemies, make calls immediately - hesitation wastes the information
Pro Tips for Scan Usage
Don't Waste on Visible Enemies
Never scan areas where you already have vision. Scan is for revealing hidden or suspicious areas only.
Scan Pit Entrances, Not Interior
Remember: Scan doesn't work inside Roshan pit. Always target the entrances and surrounding areas instead.
Night Time Advantage
Scan is especially powerful at night when vision is reduced. Use it to check dark areas and common hiding spots.
Coordinate with Wards
Before scanning Roshan area, check if supports have observer wards available. Vision is permanent, scan is temporary.
Mental Warfare
Even if scan doesn't detect anything, it tells enemies you're checking that area. Use this psychology to apply pressure.
Track Cooldown Precisely
Use our timer tool to track the 4.5-minute cooldown. Knowing exactly when scan is available helps with timing objectives.
Pre-emptive Scanning
Don't wait until it's too late. If you suspect smoke or Roshan, scan early rather than waiting for confirmation.
High Ground Checks
Before pushing high ground, scan behind towers, in trees, and on cliffs to detect waiting enemies with blink daggers.
Common Scan Mistakes to Avoid
Scanning Too Early
Don't scan Roshan pit at 8-minute mark when you have no reason to suspect enemies are there. Wait for actual suspicious activity - missing enemies, Roshan sounds, or strategic timing windows.
Not Following Up
Scanning and not acting on the information wastes the ability. If you detect enemies at Roshan, your team must move immediately to contest. Otherwise, you've burned a valuable cooldown for nothing.
Scanning Inside Roshan Pit
This is the most common mistake. Scan does NOT detect units inside the pit. Always scan the entrances, not the center of the pit.
Solo Decisions
Scan is a team resource with a shared cooldown. Don't use it without communicating unless it's an emergency situation like detecting a smoke gank.
Scanning Already Visible Areas
If you have ward vision or can see enemies on the map, don't scan that area. Save it for truly hidden or uncertain locations.
Ignoring Negative Results
A negative scan (no detection) is still valuable information. It tells you that area is safe or enemies have moved. Use this info to make decisions.
Track Scan with Our Timer Tool
Never forget your Scan cooldown again. Our DotaSense tool includes a dedicated Scan timer with audio alerts and visual countdown, helping you coordinate with your team perfectly.
Frequently Asked Questions
Why doesn't Scan detect enemies inside Roshan pit?
This is an intentional game design decision by Valve. The Roshan pit interior is immune to Scan detection to prevent teams from safely checking Roshan attempts without any risk. You must scan the entrances or use wards to gain vision of Roshan attempts.
Can Scan detect invisible heroes?
Yes. Scan provides True Sight and will detect all enemy units in the area, including invisible heroes, heroes with Shadow Blade, heroes under Glimmer Cape, and even smoked heroes. This makes it incredibly powerful for detecting ganks.
What happens if two players try to scan at the same time?
Only one Scan will be used, and the shared team cooldown will be triggered. The game will use whichever Scan input was registered first. This is why communication is essential - coordinate with your team to avoid confusion and wasted cooldowns.
Does Scan detect Techies mines?
Yes. Scan reveals all enemy units and objects, including Techies' Remote Mines, Proximity Mines, and other placed objects like wards, Plague Wards, Serpent Wards, etc. It's a valuable tool for detecting mine fields before pushing.
Should I scan before every Roshan attempt?
Not necessarily. If you have dominant map control, wards around Roshan, and know where all enemies are, scanning might be a waste. Save scan for uncertain situations when you suspect enemies might be hiding or setting up around the pit. Strategic scan usage is more important than routine scanning.
How large is the Scan detection area?
Scan has a 900-unit radius detection area. For reference, this is similar to the cast range of many medium-range abilities. It's large enough to cover most jungle camps, choke points, or areas around objectives effectively.
Does the enemy team know when they've been scanned?
Yes. When Scan is used, both teams can see the scan circle on the map. If enemies are detected, they will know you've scanned them. This means Scan has a psychological element - enemies know you're looking for them and might change their plans.