Harry Potter and the Deathly Hallows - Part 1

This trophy is earned by stunning and defeating enemies while under your cloak. To 'stealth' stun an enemy, simply put on the invisibility cloak with . Then, walk up to an enemy. Walk close enough to where your spell will hit him, but not close enough to give yourself away. When you are close enough, hold the button to cast Protego. The enemy will (most of the time) fall down and disapparate. Repeat this 49 times and the trophy will pop. Note that this is cumulative throughout different playthroughs.