The Hidden Skills are special moves that Link can learn in Twilight Princess. There are seven total. Each is learned from the Hero's Spirit after Link howls at a Howling Stone in wolf form. The Hero's Spirit will then appear somewhere around Hyrule, and Link must go there as a Hylian to learn it.
The first Hidden Skill is the Ending Blow. It is the only one required to beat the game. The move is performed by Link targeting a fallen enemy, and, as the "Finish" prompt appears at the bottom of the screen, pressing the A button. Link leaps into the air and lands on the enemy, sword first. The move is an instant kill to any enemy, regardless of health.
This is the only skill that is not learned from a Howling Stone. When Link heads to the Forest Temple, he finds the Hero's Spirit waiting in his golden wolf form just outside.
The Shield Attack is the second Hidden Skill learned. Executed by thrusting the nunchuck forward or in the GCN version, by pressing R after L-targeting, Link thrusts his shield forward. Its uses include stunning enemies and reflect certain projectiles.
The third move learned is the Back Slice. By jumping left or right while targeting and continuing to hold that direction, Link will roll sideways, circling the enemy. Attempting to attack during this roll will make Link perform a jumping slice.
The Helm Splitter is the fourth move. If Link performs the Shield Attack and successfully stuns the enemy, he has the option to do the Helm Splitter. The prompt "Helm Splitter" will appear below and upon activation, Link shall jump above the enemy, striking their head and landing behind them. He then has the opportunity to strike the enemy one last time, inflicting maximum damage.
The Mortal Draw is the fifth Hidden Skill. Being in close presence of an enemy while not targeting and with the sword sheathed with have the "Draw" prompt appear. Pressing the action button makes Link perform a devastating blow to enemies.
The Jump Strike is the sixth Hidden Skill. As an upgraded jump attack, Link gets the ability to charge it by holding the attack button. Doing so makes Link focus his blade. Letting go after a finished charge makes Link jump, swinging his sword wildly and create a shock wave upon landing. It can take out multiple enemies at once.
The Great Spin is the seventh and final Hidden Skill. At full health, Link's spin attack becomes more powerful, has greater range and boasts a red radius.