

Since the Blade Mail returns damage on the unit that attacks the owner, you can use Book of the Dead units to attack and the melee Necronomicon Warrior will die quicker to return 800 damage.Therefore, Techies' mines, Witch Doctor's Death Ward and Shadow Shaman's Mass Serpent Ward won't affect their main hero as they are considered separate units. The return damage is only dealt to the unit who attacks.

However, do make sure that you yourself can take the damage you'll be receiving, else you'll just be helping the enemy instead. For example, you can kill (or severely damage) Bloodseeker by walking around with Rupture, or Tinker by staying under his March of the Machines. A good situation to use Blade Mail is if you're inflicted with a heavy damage over time ability.And even if you cannot do that, it could make the enemy hesitant to attack you for 5.5 seconds. If timed properly, some heroes can get killed just from their own damage. Buy it as a counter if the opposing team has high damage (crits, nukes or attack speed) and have low health.It can be useful to get Blade Mail if you get outcarried, to counter the DPS and turn the enemy's damage against them.Heroes like Ursa, Spectre, and Abaddon are good examples of said resistant heroes, as are items such as Pipe of Insight or Heart of Tarrasque. Enemies with copious amounts of damage resistance or high health could very easily ignore Blade Mail's ability.It is a powerful counter against Bloodthorn and Silver Edge to prevent enemies from attacking you while under the debuff.Enduring tons of damage Wraith King can have breathing space.
