Abaddon

Abaddon the Lord of Avernus is a melee strength Hero known as one of the most versatile characters in Dota due to his rather low mana dependence, short spell cool-downs and a large number of viable item choices. His ability to help sustain his allies and himself and his strong tower diving capacity gives him solid lane presence. Many of his abilities offer a large sum of utility, which makes him a strong support Hero. Mist Coil serves as both a single target nuke and heal that helps shift the sustainability of both allied and enemy heroes in a lane at his will, though sacrificing a portion of his own health. Aphotic Shield holds as one of the most useful abilities in the game, able to shield a target from some damage while also able to reflect said damage to a huge area. The most important aspect is how it is able to dispel many status effects such as slows and stuns. His other abilities allow him to become a mix between a semi-carry and tank. Abaddons passive, Curse of Avernus, allows his attacks to not only slow down his enemy target, but increase the attack and movement speed of any ally attacking the same target. With his ultimate, Borrowed Time, Abaddon is able to shift all non-HP removal damage he receives into health. When not on cool-down, Borrowed Time may activate passively when Abaddons health falls under a certain threshold, even under the most dire situations. Due to his powerful spells and versatility, Abaddon is an excellent addition to any team.

Tips

 * Remember that Aphotic Shield can remove stuns and slows from its target, you can use this to save your allies from many sure kill situations.
 * Most veteran players will pay attention to when Borrowed Time activates and will not hit you until its duration has expired, you can however heal yourself using Mist Coil during this time, or by putting yourself among enemy creeps or Damage over time skills that have already been cast such as Jakiro's Macropyre. Pay attention however that your ultimate has a relatively short duration.
 * Sometimes it might be a good idea to burst Aphotic Shield on purpose by casting it on the same target if enough damage has not been absorbed.
 * Since Culling Blade can kill Abaddon even through Borrowed Time you might be able to bait out the skill from an enemy Axe by manually activating your ultimate just before you hit the threshold.
 * Abaddon is a very durable hero due to his unique ultimate, however do not let this fool you into diving enemies in confrontations where retreating is the better option.
 * Early game it is possible to harass enemies by casting your Aphotic Shield on creeps that are about to die causing all heroes who move in for the last hit to take damage. You will need proper mana management to keep this up though.
 * If you are playing the team's support hero it is usually wise to max Mist Coil and Aphotic Shield first before getting any points in Curse of Avernus as your first two skills provide a lot of utility early game ranging from healing, to debuff removal, protection and even denying yourself if needed.
 * If you are planning on playing the team carry early points in Curse of Avernus will give you much needed chasing power and increased damage output and will also apply the same to your allies. In this case it might be a good choice to max Aphotic Shield before Mist Coil because you are likely to be diving the enemy a lot which will assure that your shield will burst quickly, allowing you to repeatedly cast it on yourself. Though trying to be the carry for the team is not recommended as Abaddon has much more utility as one of the most durable support heroes in the game.
 * Curse of Avernus can have defensive uses as well, such as hitting an enemy that is chasing your ally to slow them down. You can also use this to save yourself as well under certain circumstances as hitting your target will reduce their movement speed by 20% while give you a 15% movement speed buff. That short boost of movement speed can sometimes save you or your allies.
 * Note that Curse of Avernus's debuff is not a unique attack modifier and fully stacks with actual Unique Attack Modifiers. Considering this you may sometimes want to buy an Orb of Venom which allows you to slow down a hero up to 32% when used in conjunction with your passive. When playing a carry Abaddon this aids you greatly with chasing down heroes. The same can be said with a Sange and a completed Sange and Yasha that gives you both a movement speed boost and an additional slow.
 * Due to his ultimate Abaddon is one of the few heroes that can dive towers even in early stages of the game, to add with his ability to chase down heroes you may also want to purchase a Mask of Madness as the extra damage Abaadon takes from activating it will not matter because of Borrowed Time.
 * Against less experienced players it is actually possible to 'initiate' with Abaddon in a team fight by diving into them and absorbing most of their skills and disables since in most cases Abaddon cannot be focused down before his ultimate. This will allow your teammates to enter the fray without the fear of being disabled themselves. Of course this strategy is very unlikely to fool more veteran players.

Trivia

 * Abaddon's title, Lord of Avernus, is a reference to the famous crater in Italy, which was, in ancient times, believed to be the entrance to the underworld.
 * In DotA, Abaddon's third skill was originally called "Frostmourne." It was changed in transition to Dota 2 due to copyright reasons, since Frostmourne exists as a famed weapon in the Warcraft universe. Similarly, his first skill was originally named Death Coil, but was likely changed to differentiate it from the ability used by death knights in the Warcraft universe; one of Abbadon's responses when using Mist Coil references the original name.
 * In the Bible, is the name of an angel, who will rise from the Abyss and command an army of locusts.
 * Taking his rival taunt into account when he kills Nyx Assassin it can be assumed that Abaddon's helmet is in fact fashioned from another Nyx Assassin's head that he has slain in the past as it very much looks like the head of Nyx Assassin complete with the mandibles and its horn.