Phoenix

Phoenix is a flexible and unique ranged strength hero with a plethora of powerful abilities that inflict heavy damage over time on its opponents at the cost of its own health. It can be played as either a support, initiator or semi-carry. Icarus Dive can serve as either a harassment tool, an initiating maneuver or an escape mechanism, all the while slowing and damaging opponents in its path, while its Fire Spirits burn and cripple the opponent's attack speed, making it a potent anti-carry. Sun Ray projects a powerful beam in front of Phoenix that burns enemies for a percentage of their maximum health while sacrificing some of its movement speed, and, if it ever sees fit, it can end its current life to turn into a searing Supernova. Surviving this stage of its life cycle allows Phoenix to reemerge in full strength, stunning all nearby opponents and with all cooldowns refreshed, ready to inflict havoc on its foes once again.

Tips

 * Since most of Phoenix's abilities cost a percentage of his health to activate, health regeneration items are very useful. Urn of Shadows, Mekansm, Pipe of Insight and Heart of Tarrasque are good examples of such items.
 * It's very helpful to prioritize a Shiva's Guard as your first or second major purchase, as its passive attack slow works during Supernova. With a bit of timing, you can also use Shiva's while Icarus Diving for a long ranged AOE disable.
 * Buying Eul's Scepter of Divinity can sometimes be a good investment, as you can still Sun Ray while under the effects of Eul's, and you can use it while diving to disable an enemy from a long distance.
 * Fire Spirit's attack speed reduction is great to mess up the enemies' last hits. Also, if used right before Supernova, it will make killing the sun harder.
 * Phoenix can be used both as a semi-carry and a support. If going for the former, take the mid lane and buy items to make you harder to kill. If you're supporting, consider going for cheap healing items such as Tranquil Boots, Urn of Shadows and a Mekansm.
 * You can go to the area around Roshan's pit and use Sun Ray to quickly and safely check if the enemy team is fighting Roshan.
 * You can give your team a significant initiation advantage by flying over the enemy team with Icarus Dive and rapidly covering the area in Fire Spirits. Fire Spirits will be easier to land from close proximity, but their high range can also allow you to hit spread-out team members. While the enemy team's movement and attack speed has been slowed, Supernova is a much more effective ability.
 * If you are confident about your team's follow-up, you may be able to soak up some extra damage before using your ultimate, thus relying on your team rather than your own short-lived disables to protect the Supernova. If you're less confident, you can continue the Icarus Dive to a point where Supernova can still affect some enemies, but to eliminate it the enemy heroes will have to slowly run towards you and your team and ignore the latter if they still intend to focus you. If you're not confident at all, you can resume support with your Sun Ray instead of using Supernova since the Icarus Dive will return you to your original position by default.
 * Magic Stick and Magic Wand are even more effective on Phoenix than most other heroes because his abilities cost both HP and mana, decreasing scenarios where you only use the items to gain just enough mana for casting an ability.

Trivia

 * Phoenix's name in DotA was Icarus. It was removed during its port to Dota 2 for unspecified reasons.
 * The lore of Phoenix's sub-abilities Toggle Movement, Launch Fire Spirits, Stop Sunray and Stop Icarus Dive has a words such as SQWARK!, PKAWW! BOOM, CHIRP!, and SCREE! which are associated with the sound of those abilities.
 * Phoenix is one of the few heroes that have responses that are voiced by themselves.