Magic
From PinataIsland.info, the Viva Piñata wiki
in a multiplayer game the other players(non owner of the garden) can gain magic and fill there triangulated circle with colors by planting seeds and watering plants. once the triangulated circle is full of color aka magic. you can then use the magic in a multitude of ways. such as healing sick pinatas, making a pinata happy and at full candiosity, and tinkering items at 100% efficiency.
