The card's effect allows you to gain 3000 Life Points, but only when control is shifted to your opponent. A way to benefit from this is using "Fairy's Hand Mirror" against your opponent when they use a Spell Card that allows him/her to take control of one or more of your monsters.
"Shien's Spy" works well with "Griggle". You hand over "Griggle" to your opponent, gain the 3000 Life Points, and then attack "Griggle" with a high-ATK monster.
"Fairy's Hand Mirror" would also be particularly good against "Snatch Steal", so not only would you receive +3000 Life Points during the control shift, but "Griggle's" low stats would offer a good way of dealing difference damage to your opponent. Another tactic would to leave "Griggle" in play to benefit from the +1000 Life Points bonus from "Snatch Steal".