It lets you keep your best creature in play
If one does not set up their offense in time, they may lose Pokemon needlessly to opponents with faster decks
So in a theoretical offensive situation, you can perhaps transform another battle with it, while pinging a potential defender to push more damage to any other relevant target(s)
Any monster attempting to destroy this card by battling it would see their attack points become 0
Personally despite having opened an absolute load of Burning Shadows booster boxes I only ever even saw one of these cards
What to Change Out: 1 Felling Blow U 2 Apothecary Stomper C 1 Rampaging Baloths R 2 Elfsworn Giant C 4 Druid of the Cowl C 2 Mild-Mannered Librarian U 2 Magnigoth Sentry C In: 1 Prime Speaker Zegana R 3 Mossborn Hydra R 1 Loot, Exuberant Explorer R 1 Llanowar Elves C 2 Bonny Pall, Clearcutter R 2 Insidious Fungus U 2 Summon: Fenrir U 2 Spinner of Souls R Total wildcards needed : 0 Mythic Rares, 9 Rares, 4 Uncommons, 1 Common