Necrophos

Rotund'jere the Necrophos is a ranged intelligence hero. His abilities are most effective in team fights where he can damage enemies and heal allies simultaneously, while picking off key enemy heroes with his ultimate. Necrophos is most dangerous when his enemy is severely injured, instantly killing them with his ultimate while recovering over time after killing his foe. Necrophos is naturally fragile, but his mechanics require him to stay in the midst of encounters; it is for this reason that he depends on items to prevent his death. Ideally, by casting Death Pulse repeatedly, he and his team are able to stay alive while the enemy team's health is gradually sapped by Heartstopper Aura, which reduces enemy HP by a small percentage each second. Because his abilities are suited to prolonged encounters, he must build items which allow him to survive for as long as possible against his enemies. His ultimate, Reaper's Scythe, has its damage increased by how much of their maximum HP the target is missing; meaning that an enemy that is close to death will be killed outright by it. Upon attaining a kill, Sadist restores Necrophos's mana and HP over a short time, allowing him to continue fulfilling his role in encounters. Necrophos is best understood as a hero who is weak at the beginning of a fight but becomes more dangerous with each passing second.

Tips

 * Taking one point in Heartstopper Aura in the early game allows Necrophos to harass enemy heroes by simply standing near them. Its massive AOE will usually cause heroes to run out of their early game regeneration items quite fast.
 * Note however that the aura affects enemy creeps, and thus putting points in it will push the lane. Should you lane with a farm-dependent carry, it is unwise to push as it makes their farm more difficult and leaves both of you more vulnerable to ganks. Putting one or at the most two points in it is appropriate for early game.
 * The philosophy behind Reaper's Scythe is that (owing to Sadist) it will return its mana expenditure if you secure a kill. There are several situations in which this ability should be used purely for its stun, such as interrupting channelled ultimates (such as those belonging to Pudge or Enigma) or preventing an enemy hero from escaping. Remember that the stun goes through magic immunity, although the damage will not.
 * At level 3, Reaper's Scythe will kill targets at 40% or less hp (with Aghanim's Scepter it's generally any amount under 45%). Remember to factor in Magic Resistance before you attempt to execute an enemy hero with it. Remember that this ultimate adds additional time to its victim's respawn timer and with Aghanim's Scepter it prevents them from buying back. In later stages of the game this can prove very important in removing key enemy heroes from the fight for a very long time.
 * The Reaper's Scythe instant-kill HP threshold, with the base 25% magic resist factored in and without Aghanim's Scepter, can be calculated by multiplying the enemy max health with the constants: 3/13, 9/29, or 27/67 for each respective level of the ultimate. With the Scepter, the values change to 9/29, 27/67, and 9/19. Example: If Windranger has 700 max health; 700*3/13 = 161. Id est, she must have 161 or less HP to be killed by level 1 Reaper's Scythe without Scepter.
 * Keep in mind that Reaper's Scythe is not a channeling ability, meaning you can move the moment you have cast it. As such, it can be used to escape ganks and chases. However, be sure of two things before using it this way, first of all, make sure the 1.5 second stun can actually save you, and even if it can save you, consider secondly if it is worth using your powerful ultimate solely for saving yourself. Otherwise it is most likely more beneficial to your team to accept your death and save your ultimate for the next encounter.
 * Because you can cast during the stun, you can use it to initiate on an enemy hero to keep them from escaping or using Black King Bar assuming you can cause enough damage in 1.5 seconds. You can instant-kill with this tactic if you are paired with a high burst damage hero such as Huskar or Lina or Lion, or if you are in possession of a high level Dagon and an Ethereal Blade
 * Necrophos can very easily be built as a tank and in most circumstances should be; you may gear for Strength (he does not need excessive Intelligence as his autoattack is not too useful, and Sadist refunds mana for each kill he gets). The reason he is usually built as a tank is because he needs to stay alive in violent encounters to heal his allies (a good enemy team will focus him first), and also because the longer he is alive for, the more damage his aura will do and the better chance he has of landing a crucial Reaper's Scythe.
 * Though it may be a bit wise to build some mana pool increasing items such as Point Booster or other Intelligence items anyway, because if Necrophos has used all his abilities and failed to get a kill, he can wind up unable to cast any more of his spells, and if his auto attack is not too great, getting last hits to regenerate some mana can be problematic.
 * Utility items, such as Mekansm and Pipe of Insight are more useful for Necrophos, because of Heartstopper Aura he can inflict constant damage simply by avoiding death.
 * Necrophos is effective against invisible heroes that tend to stalk their prey as his Heartstopper Aura does damage while they are in stealth, his Death Pulse hits invisible units, and his Reaper's Scythe will prevent them from escaping via invisibility before they die. He is also very good against heroes with abilities that deplete their own HP such as Pudge, Slark, and Centaur Warrunner (Huskar is an exception since his Berserker's Blood will almost always prevent you from killing him with Reaper's Scythe), but Necrophos should first be durable enough to take on these kinds of risk/reward heroes.
 * Necrophos's role is notoriously debated; while his abilities appear supportive at their core, his Reaper's Scythe is a tool used to secure kills only for himself (much like Axe's Culling Blade). This is atypical for a standard support hero, because supports usually attempt to confer gold and experience to the team's carry. The duplicity of his carry/support role stems from his unique stance in encounters; his kit is largely supportive until an enemy hero grows weak, at which point Necrophos has the capacity to kill said enemy himself. He is best viewed as a utility focused semicarry, rather than a full fledged support hero, in a similar vein to heroes like Tidehunter or Windranger.
 * Necrophos is countered in lane by any hero with high HP regeneration, such as Dragon Knight and Quas-focused Invoker, or a hero with lifesteal capabilities; because he relies on inflicting constant, gradual damage with Death Pulse and Heartstopper Aura. Heroes with these attributes will resist this in lane against Necrophos, keeping high enough HP to prevent death by Reaper's Scythe.
 * As Necrophos's survivability heavily relies on his ability to spam Death Pulse you need to be wary of heroes with silence such as Drow Ranger, Silencer and Death Prophet. Ancient Apparition can also greatly cripple you with Ice Blast as this ability prevents HP from regenerating for an extended period of time.
 * Dagon is more useful on Necrophos than other heroes because it not only deals burst damage, but also allows you to quickly deal more damage from your ultimate.
 * Ethereal Blade can be used in conjunction with Reaper's Scythe and Death Pulse to deal significantly more damage. If you are also in a possession of a high level Dagon, a quick Reaper's Scythe to Ether Blast to Energy Burst combo can decimate full health enemy heroes with total health points lower than 2000, assuming they have the standard 25% magic resistance. It is worth noting that Ether Blast temporarily increases the magical damage dealt per missing health from the standard ( 0.4/0.6/0.9 (0.6/0.9/1.2*) ) to ( 0.56/0.84/1.26 (0.84/1.26/1.68*) ) thus also increases the instant-kill threshold.
 * Assuming a level 5 Energy Burst and a level 3 Reaper's Scythe with an Aghanim's Scepter is used against an enemy with 25% magic resistance while being ethereal, you will deal 840 damage from Dagon and 1058.4 damage from Reaper's Scythe, to a total of 1898.4 damage (not including damage from Ether Blast and Reaper's Scythe damage due to it). If the match reaches the late-game, you still can burst down a full health non-magic-immune enemy carry with standard magic resistance during teamfights, potentially turning it into your team's favor.
 * Necrophos can be a viable choice when you decide an defensive trilane and the enemy has a tanky offlaner, so that their health slowly drains and may reach a level when you and your allies can subdue and kill the enemy.

Trivia

 * Necrophos's response, " necr_level_04.mp3  My name is lesion!" probably has to do with the Bible passage Mark 5:9, that reads in the NIV, "Then Jesus asked him, 'What is your name?' 'My name is Legion,' he replied, 'for we are many.' "
 * Necrophos's response, " necr_ability_reap_03.mp3 You reap what you sow." might be from the Bible's passage Galatians 6:7 "Do not be deceived, God cannot be mocked. You reap what you sow."
 * Necrophos's alternate/fun name was "A Phoe Gyi", which means "an old man" in the Burmese language. It also sounds similar to 'a fogey', which is an elderly, normally grumpy individual.
 * Necrophos's original title in DotA was "Necrophiliac"; his designer altered the name to "Necrolyte" (a portmanteau of nekros (νεκρός), the Greek word for corpse, and acolyte, a religious attendant) upon realizing its implied sexual connotation.
 * In the November 21, 2013 update, Necrolyte's name was changed to Necrophos, likely to avoid copyright issues with Blizzard.
 * In the same update, Necrophos's voice processing was changed a bit to sound more distinct from . However, there was a bug that made the in-game processing much deeper and slower than it should have been.
 * Necrophos's responese "Red Death" could be a reference to the Edgar Allen Poe short story of the same name.