(This is during Duellist Kingdom, where high-level monsters do not require tributes.)
In Episode 033, Yugi has Gaia the Dragon Champion on his field, and Jounouchi has in his hand Red-Eyes Black Dragon, Graverobber, and Kunai with Chain. He thinks it's hopeless, since even if he summons Red-Eyes, Gaia still has greater strength. But he draws Copycat, inspiring a strategy: He summons Red-Eyes, then activates Graverobber from his hand as a Spell Card, stealing Yugi's Summoned Skull. Next he uses Copycat as a Spell Card, which apparently allows him to mimic any card which Yugi has used; he chooses Polymerization, and with it he fuses Summoned Skull and Red-Eyes to summon Black Skull Dragon, a monster that can overpower Gaia.
Meanwhile, I think: Wouldn't it have been simpler to use Kunai with Chain? Red-Eyes has 2400 ATK, and Gaia has 2600. The Trap Card Kunai with Chain can add 500 additional ATK to a monster. If he had summoned Red-Eyes and allowed Yugi to attack with Gaia, he could have activated Kunai with Chain and defeated Gaia without his original needlessly complex strategy, saving several cards that could be useful later. While Kunai with Chain did end up being useful later itself, Graverobber and Copycat, I think, are more worth saving.