He is a gigantic figure - by far the largest enemy seen in the game - and is not only extremely powerful, but is also accompanied by a horde of lesser enemies as well as his two henchmen - Horse Head and Ox Face.
His face is the target of attack, and after a certain amount of damage his face will detach from his skull and start flying around the arena. He attacks when the Spelunker gets near by smashing his fists upon his throne, causing three skulls to fall from the ceiling directly above the Spelunker.
King Yama will also spit Imps out of his mouth and try to use his fists in a punching attack if the Spelunker gets close enough to his head or chest area (such as by climbing onto his shoulders). He might also open his fists, spawning Magma Men that will jump out.
After taking enough damage or having both his fists destroyed, his face will detach from his skull and begin floating around the arena, engulfed in flame, crashing upwards into ceiling causing skulls to fall and spitting fireballs that turn into Magma Men downwards. Be advised that during this second phase, if you move within two blocks of his head, it will bounce upwards, before settling down at its original Y co-ordinate, so leave a few blocks when throwing sticky bombs.
He can be attacked using ranged weapons or Sticky Bombs. If shot with the Camera during his first phase, he will immediately skip to the next one. Doing this again on his second phase will only stun him. Alternatively, King Yama can be defeated in a single hit by telefragging his head, or freezing his head and hitting him (1st phase) or letting his head fall into the ground and get crushed (2nd phase).
If the Spelunker brings the Eggplant to him and throws it at his head then King Yama will turn into an Eggplant Monster that will be completly immovable and constantly sweat. This will also set Yama's health to 2 points and deal 1 point of damage because of the Eggplant throw, effectively making him have 1 point of health, then any hit at all will kill him. Though this strategy makes King Yama much easier to defeat, the challenge of bringing an Eggplant to him makes it not so viable. It's also worth noting that every Eggplant will set Yama's health at 2 points, therefore making it impossible to kill Yama just by throwing Eggplants.
King Yama's hands and face are physics items, and may be picked up, the hands will normally try to go back to their position by moving back slowly, as long as Yama is still alive and will die instantly placed inside lava. The hands will keep their smashing animation once started, and will "hit" while being carried by the Spelunker, while this won't deal damage at that moment, it will once the hands are thrown by the Spelunker, dealing 2 points of damage, if the hand is left into Spikes after the smashing animation, the hands will get killed by the Spikes, but will still deal damage to the Spelunker.
King Yama's face won't move during the first phase, but will still be able to spit Imps if he started before the face was picked up by the Spelunker. Yama's face won't be able to take damage from thrown items nor crushed if it's placed under the height of his hands, however, sticky bombs will still stick to him and the explosions will still deal damage, this also applies to the whip, but the Spelunker won't be able to deal damage with thrown items nor use the Shield to crush his face.
Because of this property of the head, an Eggplant used on Yama's face after placed under the height of his hands will set his health to 2 as per usual, but the Eggplant will continue flying and won't deal the point of damage, leaving Yama with 2 points of health, requiring two hits to be killed. This is important to keep in mind if the player wishes to kill King Yama with a Snowball or some other item.
When King Yama is defeated, you will unlock Yang, whom you play as in the tutorial. You will also receive an extra 100,000 gold by finding the Golden Trophy. Additionally, with enough bombs you can destroy the bricks of King Yama's Throne which contain a ruby in every block. The 44 rubies that can be mined from the throne are worth a sum of $140,800.