Infernal Blow

Infernal Blow is a melee attack skill that converts 60% of Physical Damage to Fire Damage, applying a special debuff to enemies. When the debuff reaches six charges, expires, or the enemy affected by the debuff dies, it releases an explosion that deals fire damage to nearby enemies. This skill requires a sword, axe, mace, staff or unarmed.

Skill functions and interactions

Damage conversion: Like all converted damage, the fire portion of Infernal Blow's damage will be modified by both fire damage increases and physical damage increases.

Duration: If the debuff caused by Infernal Blow is still active when the monster dies, it will explode even if Infernal Blow was not the killing blow. That makes this skill very effective with Melee Splash Support or Ancestral Cry.

Debuffs: When the attack made with Infernal Blow hits an enemy, it applies two debuffs: the first debuff can stack up to six times and creates an explosion that deals damage based on your weapon damage when it reaches full charges or when it expires. The second debuff causes the enemy to create an explosion that deals damage scaling with its maximum life when it dies.

Explosion: The corpse explosion deals fire secondary damage in an area and cannot be reflected. It is neither an attack nor a spell, so in particular it is not affected by modifiers to melee damage, weapon damage or spell damage, but is affected by Elemental Damage with Attack Skills. While in a party, the explosion ignores the increased life added for each player beyond the first and treats the monster's life as if you were solo.1

The charged debuff explosion deals the exact same damage types as the melee hit, plus area damage.2 Ruthless blows (Ruthless Support) are calculated differently depending on how the charged debuff explosion was caused. If the debuff reaches 6 stacks, then the hit that applied the 6th stack determines whether or not the explosion is Ruthless. If the debuff expires for any other reason (such as the monster dying) then the hit that applied the 1st stack determines whether or not the explosion is Ruthless.3

Monster Types: Magic (blue named) and rare (yellow named) monsters, and unique monsters (orange named) can be exploded.

Area of effect modifiers will only apply to the explosion itself, not the melee attack.

References

1. ↑ Mark_GGG (February 3, 2013 5:35 AM). "Devs and other GD people - Kripps Death a good thing". Path of Exile Forum. Retrieved August 2, 2013.

2. ↑ Mark_GGG (Jun 6, 2018, 6:22:38 PM). "So I still don't understand the new mechanics of Infernal Blow at all... (Page 1)". Path of Exile Forum. Retrieved November 13, 2018.

3. ↑ Mark_GGG (Jun 7, 2018, 5:47:47 PM). "So I still don't understand the new mechanics of Infernal Blow at all... (Page 2)". Path of Exile Forum. Retrieved November 13, 2018.