From Dota 2 Wiki
| Battle Fury|
|The bearer of this mighty axe gains the ability to cut down swaths of enemies at once.|
- Only increases base damage and that provided by attributes. Attack damage bonuses are not increased.
- The bonus damage does not apply when attacking friendly units (i.e. denying own creeps).
- When the owner's attack type changes to ranged or melee, the attack damage bonus adapts immediately.
- Quell fully works with crits, cleaves and lifesteal. When having cleave, attacking a creep cleaves the increased damage in the area.
- Elder Dragon Form's splash also splashes the increased damage when attacking a creep.
- The damage Moon Glaive bounces are not increased, since they are based on the attacker's attack damage value.
- Psi Blades will spread the increased damage when attacking a creep.
- Cleave damage is reduced by Damage Block.
- The complete area is shaped like an isosceles trapezoid in front of the attacking hero.
- Fully stacks with other sources of cleaves. Each source of cleave works completely independent.
- Does not cleave upon attacking wards, buildings or allied units. Wards and buildings are unaffected by cleave.
- Despite the visual effect, cleave damage is applied instantly in the whole area.
- Ranged units cannot cleave.
- Anti-Mage needs Battle Fury to farm, since he is terrible without items and has trouble farming fast without it. Combined with Blink, he can flash-farm the jungle and quickly build his much needed items if not ganked.
- Phantom Assassin does not necessarily need it, but it helps her farm and build items quicker. This will reduce her ability to get early kills since she would have to farm in times she could fight.
- Juggernaut can farm really fast with it when combined with his base attack time. He can pick up the Ring of Health and Void Stone at the side shop during the laning phase, allowing him to use his abilities more often and ignore harassment.
- Battle Fury is a must for a physical damage-built Ember Spirit, since almost his entire damage output relies on Sleight of Fist, which can deal enormous damage with Battle Fury but little without it. Ember Spirit is also the most reliable carrier of multiple Battlefuries, since each one greatly increases his damage and unlike other carries, he stays safe during Sleight of Fist while it greatly weakens the survivability of other carriers by having multiple Battlefuries.
- Tusk can get Battle Fury if he is built to get the most out of his Walrus PUNCH!, which you will see many do. Battlefury gives him the ability to damage more than 1 enemy with his punch, giving "Carry Tusk" more teamfight presence.
- Troll Warlord can get Battlefury, but this is very situational. Troll Warlord can be a melee hero and can farm the jungle much more efficiently with Battlefury, but he needs items which help him fight and deal damage such as Daedalus and Monkey King Bar. Furthermore, Battlefury's cleave will not work while you are ranged, so you will lose the cleave effect when attacking opponents from range.
- The battlefury is good for farming but not for fighting because the damage per gold is low. Don't get it if the enemy is very aggressive and your team asking for help unless the enemy team uses illusions and summoned units.
- Effective against illusions, summoned units, jungle stacks, ancient stacks and mega creeps.
- A battlefury allow to farm faster than a Midas for a melee hero. You can get this item after boots start with a ring of regen if you are laning or get damage if you are jungling, then get a mobility item like Blink Dagger to reach camps faster.
- The cleave benefits from critical hits, including those from items and ignore the armor value and evasion.
- Having Battlefury can help greatly against an enemy Nature's Prophet, since some carries have little means to escape his Sprout without it (the most obvious being Juggernaut and Sven)
- Melee heroes with high attack speed can push far more effectively with Battle Fury, even in late game. Critical hits help too.