Fading is a keyword ability.
It is an ability that limits the time a permanent will stay on the battlefield. A permanent with fading will enter the battlefield with a set number of fade counters and then, at the beginning of its controller's upkeep, its controller must remove a counter from it. If that player is unable to remove the counter, they must sacrifice it.
Andrew casts a Tangle Wire. When Tangle Wire enters the battlefield, it will enter with 4 fade counters. On each of his upcoming upkeeps, he will remove one of these counters from Tangle Wire until there are none left. In his next upkeep he will be asked to remove a counter, but because he will be unable to, he will have to sacrifice Tangle Wire.
- 702.31a Fading is a keyword that represents two abilities. “Fading N” means “This permanent enters the battlefield with N fade counters on it” and “At the beginning of your upkeep, remove a fade counter from this permanent. If you can’t, sacrifice the permanent.”