Inspiring Easel is one of those cards players keep asking about. Here is, in plain words, what its official text says, the rulings published by Wizards of the Coast, and the combos players actually run.

Official card text

: Add one mana of any color. Spend this mana only to cast an instant or sorcery spell. : Choose an instant or sorcery card in your hand. It perpetually incorporates and gains "When you cast this spell, copy it. You may choose new targets for the copy." Activate only as a sorcery.