The elemental magic forms that Merida's arrows take through the four magical charms of Earth, Fire, Wind and Ice in the video game version of Pixar's Brave.
Earth: The charm powers up Merida/your bow and sword with earth magic, it can bring extra damage to root and flying monsters, it can even use its magic to make objects grow. You get it from the witch so Merida could break Mor'du's cures and have a fighting chance with the monsters.
Fire: The charm powers up Merida/your bow and sword with fire magic, it can bring extra damage to wood and ice monsters, it can even use its magic to burn objects. You find it in the first ruin in one of the forests Merida comes across on her journey, after she has her first run in with Bear Elinor before she dashes off.
Wind: The charm powers up Merida/your bow and sword with wind magic, it can bring extra damage to rock monsters, it can even use its magic to lift objects into the air. You find it in ruins near the sea.
Ice: The charm powers up Merida/your bow and sword with ice magic, it can bring extra damage to fire monsters, it can even use its magic to freeze and cool objects. You find it on a shrine in a land frozen in ice.