Song of Time
In Ocarina of Time,
the Song of Time can be used in the Temple of Time to unlock the passage to the Master Sword once you have the three Spiritual Stones. It can also be used to get rid of certain blocks.
In Majora's Mask,
the Song of Time warps you back to the dawn of the first day. Any items or rupees you have when playing the song will be lost.
Games Featuring This Song
Ocarina of Time
Majora's Mask