Invoker

Invoker is an almighty ranged intelligence Hero, considered by many as the most complex and difficult to use. He is unique in that he possesses a total of 14 abilities in his arsenal; three of them - Quas, Wex, and Exort - are reagents and one is his special ultimate Invoke. The three abilities he learns throughout leveling up can have three instances, which serves as the basic ingredients or components for him to create a new ability using his ultimate. Once the reagents or elements are combined, he can invoke one out of ten different abilities. All of his invoked abilities are capable of a multitude of actions, from damaging enemies to aiding his allies, and even saving himself from danger. His three reagents can be upgraded up to level 7 which determines the power and potency of his invoked abilities, making it more powerful than an ordinary spell. Because of this, he can be played in almost any role possible. Invoker can be a carry, semi-carry, ganker, pusher, initiator or even tank or support (though the gold investments tank make this highly unrecommended). He is also the only hero who doesn't have Attribute Bonuses, thus he has average attributes. However, his three reagents provide passive attributes with each level, and each instance of his reagents provides a passive bonus, allowing for specialization at early levels and situational boosts at later levels.

The Invoker, though powerful on his own, is item-dependent; his top priorities are health for his survivability, mana for him to utilize more of his abilities, and damage if you want him to be a strong carry. The result is his differentiating item build in almost every different situation, mostly depending both on his own build, and his opponents' actions. He also requires fast hands, and various skills depending on the focus of his invoked abilities; examples include his need of extreme map awareness to pull off Sun Strike properly, or to have a subtle idea of prediction to pull off combos such as EMP - Tornado or vice versa. Because of this, newer players will have a hard time using Invoker. But once learned and mastered, the Invoker will rise to its full potential and playing this archmage is truly a great reward. Invoker is recommended for advanced players.

Gameplay
The Invoker is the most well-rounded spellcasting hero, due to his massive array of spells. Using his three elemental reagents and his Invoke ability, the Invoker can utilize a total of 10 different spells. Due to his complexity and fragility, the Invoker is a bad choice for newer players. With some experience, however, he becomes a force to be reckoned with. The Invoker is capable of massive area of effect damage, powerful disabling spells, very strong summons, and potent enchantments. While other spellcasters tend to be focused in one area, the Invoker has the ability to change his role at will. His spells tend to start out weaker than comparable abilities, but since his reagents have 7 levels each his potential spell power is very high. Although mastering his spells takes perhaps the most practice of any hero, he is definitely worth the time.

At level 25, Invoker has 7 points each towards Quas, Wex, and Exort, and 4 points towards Invoke. Uniquely among heroes, Invoker does not possess the Attribute Bonus ability (i.e., he cannot put points towards "Stats"). Instead, he gains a permanent attribute bonus to one of his stats each time he levels up Quas, Wex, or Exort.

Trivia

 * In the earliest version of Invoker, the order of instances mattered when Invoke was cast. Invoker had access to 27 spells, including the 10 still in game.
 * The name "Carl", in Dota 2 Invoker's responses refers to a "leaked" changelog of DotA 6.72, in which "Kael", Invoker's original name, was mistakenly translated as "Carl"..
 * One of souls contained inside Undying appears to know Invoker, calling him by the name Carl.
 * His fun name in original Dota is Kal-el, an allusion to Superman.
 * His original name is Kael, possibly based on the WarCraft Blood Elf Mage character, Kael'thas Sunstrider.
 * Invoker is (or used to be) also a Magus like Rubick, namely the Arsenal Magus.