An old associate of mine speaks impeccable Cantonese. He lived about 200 years ago. Know him? Sun Lok.
~ Maxim Horvath about Sun Lok.
Sun Lok is a brutal Asian wizard and a supporting villain of The Sorcerer's Apprentice. He was recruited by Maxim Horvath as a loyal servant of Morgana le Fay in his quest to free her, which made him become a Morganian.
200 years ago, Sun Lok met Horvath, and lent his hand in freeing Morgana. Presumably under Horvath's tituledge, Sun Lok trained and eventually became a powerful Morganian. This made him an enemy to Balthazar Blake, whom eventually battled him and sealed him within the Grimhold.
A couple of centuries later, Horvath opened the Grimhold in Chinatown, freeing Sun Lok, who then tried to attack Balthazar by sending hundreds of needles flying towards him, but Balthazar blocked them all with his coat. Then Balthazar used an air-based blast to blow him away and throw him through the window down onto the street.
As Sun Lok recovered on the ground, he ran into Dave Stutler, Balthazar's companion. At first Dave pretended to be just someone in the crowd and joined their clapping and cheering, "Are you all right? Looks like... What the... Yay. I'm like one of them". But Balthazar looked down and said, "Dave? You should run". Dave ran away fast, and Sun Lok acted quick. He wore a magic abdominal belt on his stomach, which he could use to manipulate a dragon, by waving his bronze claws over a small dragon design on the belt, transforming the fake Chinese dragon costume into life. Soon the paper dragon on the street was transformed into a real dragon, causing panic everywhere. Balthazar sent a wave of confetti across the street to reduce the panic while the dragon chased Dave throughout the buildings. Dave called for Balthazar but Sun Lok shown himself through the confetti instead. Dave attempted to fire at Sun Lok's armor with his Dragon Ring but nothing happened, which Sun Lok returned with a "I bet you can't do it" look. Balthazar soon appeared and told Dave, "You skipped the first step! Clear your mind!", which he replied, "Clear my mind? Are you insane?" Soon, the dragon climbed onto the wall of the buildings, sending a section of the emergency staircase to crash down towards the street, only to be transformed into another bunch of confetti just in time by Balthazar using transubstantial transfiguration. When Dave was finally able to focus and clear his mind, he fired his first fire shot which set the dragon on Sun Lok's armor on fire. The real Dragon lost control and Balthazar fired at Sun Lok, causing it to crash onto Sun Lok, killing him and revealing the original paper dragon carriers and its remains.
Sun Lok's personality is mostly not explored due to his minor screen time, though giving hints that he was quite aggressive, murderous and ruthless like all Morganians. He is also a cold, quiet, brutal, uncaring and destructive individual who has no lines of dialogue at all, even though Horvath said that he spoke impeccable Cantonese, which implies that the other possible reason of him lacking any lines in the film was his incapability to speak English.
He seems to prefer dragon motifs for his sorcery and hates any interference, which was due to some of his sorcery requiring a lot of concentration, breaking if any interference occurred. This is seen when his dragon belt was damaged by Dave's first fire shot, then his concentration over the conjured dragon fell apart.
He also hates to be confined within a little container, either due to being claustrophobic or simply disliking imprisonment. In either way, his imprisonment within the Grimhold indeed made him held grudge against Balthazar, which explained why he attacked him first upon their final confrontation.
Powers and Abilities
As a wizard, Sun Lok possessed some strong, magical abilities, including the ability to animate the dragon design on his belt and use it to conjure and manipulate the movements of a living dragon that was magically converted from something else into a real fire-breathing creature. Following spells and powers that he mastered are:
Animation Spell: Sun Lok's mastery over the Animation Spell allowed him to bring a dragon-like objects to life as actual, fire-breathing dragon at will. During skirmish in Chinatown, Sun Lok turned a dragon dance costume operated by several Asian men into actual dragon to chase Dave, with costume operators literally fused with it as their legs morphed into the beast's.
Sympathetic Magic: Through Sympathetic Magic, he can control creatures that he brought to life. He uses his animated dragon crest on his Dragon Belt as medium to control his dragon.
Transmutation: Sun Lok demonstrated the ability to dissipate and reform his body from a swarm of butterflies, which also implies how he manifests when released from The Grimhold.
Telekinesis: Sun Lok can telekinetically manipulate large numbers of solid objects.
So... You fight like a true sorcerer.
~ Sun Lok
During the attack on New York City's Chinatown District, the Cantonese sorcerer ambushed Dave and prepared to combat the Prime Merlinean as he tracked down Horvath who unleashed a horde of monsters all around New York. As this happens, Balthazar, through his telephatical projection due to banished into other dimension, explained that he imprisoned Sun Lok in 1532 A.D. (this contradicted Horvath’s claim in the film that Sun Lok was around two centuries prior to the film's events, indicating it to be 1800s). After a difficult fight, Dave emerged victorious and successfully beaten Sun Lok into pulp.
Suddenly, Horvath entered the scene, both disappointed with Sun Lok’s loss and intrigued by Dave’s magical powers. Just then, Balthazar’s projection appears and instructed Dave to seize the Grimhold from Horvath's clutches. Before the apprentice could do anything however, Horvath unexpectedly killed Sun Lok with the Parasite Spell as punishment for his failure and took the Asian conjuror’s catalyst with him.
Sun Lok's Belt
It was interesting to note that the three lesser mystical talents shown in the film - Sun Lok, Drake Stone and Dave Stutler - all seem to have an innate specialization in their powers, as Stone seems to favor illusory skills, and Stutler slants towards energy manipulation and control.
Had Sun Lok survived his duel against Balthazar Blake and Dave Stutler, he most likely would have had his magical energy drained by Maxim Horvath via the parasite spell in order to unseal more of the Grimhold, as evidenced by his actions to Drake Stone and later to Abigail Williams and Sun Lok's own fate in the video game adaptation.
According to Horvath, Sun Lok speaks impeccable Cantonese. However, he is never shown to be speaking English.
Ironically, in the videogame, Sun Lok is indeed able to speak, though only had one line: "So... You fight like a true sorcerer.".