Tiger had looked back and noticed yang demonstrate some of her power? It seemed interesting. He thought he might do the same. 

He let himself be carried by the vines and thanked Ivy silently. While being carried he turned back to the three of them, raising his voice a little, "I can do things like this." 

And without further ado, he charged his horns where white spheres formed right before lightning struck about 15 feet away, easily turning a patch of grass to ash.