"Turn an enemy to stone." - Ivy's description in Golden Sun: Dark Dawn.
When Set, Ivy increases its Adept's base HP by 11 and base Attack by 3. When Ivy is unleashed in battle, the user produces an effect that prevents the next one action that the target has not performed yet this turn from executing. If an enemy only has one action per turn, it will essentially be prevented from doing anything this turn, while an enemy that acts twice per turn will only act once. This effect has the "strikes first" property, meaning it will be the first performed action in a given turn regardless of the agility rating of the user and any other combatant in battle. In Dark Dawn, Ivy's unleash animation visually resembles the user summoning the 3D model of Ivy above the target's head while the background dims. Ivy floats above the enemy as a circular field of gray stone sand surrounds and wisps around the target, and two large green "eye flash" star shapes appear at Ivy's eyes. Immediately after this, the enemy's idle animation suddenly freezes in place and turns gray as though petrified. Then a puff of smoke is emitted at the base of the enemy, and all the sand disappears, the background returns, and the enemy regains its color, though it won't resume its idle animation until the game gives the message "[enemy] is unable to move!"
How to GetEdit
Ivy is well hidden in Passaj: after activating the Grave Eclipse, enter Passaj through Passaj Mountain Climb pick up the Old Rag off the table in the northwest room of the inn. Find the female NPC in violet on a bed, and show it to her. After a brief cutscene, follow her to the room you found the rag in. After another cutscene, speak with the left male NPC twice, and ask him to help you. He'll disappear into your party. Walk back to the cave before the elevator down and inspect the diagonal Zol stone, and you automatically acquire Ivy.
Ivy's Japanese name, Medusa, is a reference to the Greek mythological figure, more so with its unleash effect of turning people to stone.