It had taken a lot of money and considerable effort for Lin Yao to accumulate over 4,000 green energy points. Although they had not vanished overnight or reverted to their previous condition, there was not much energy left and Lin Yao was feeling the pinch.
His mood only recovered after a long while.
'I have to think positive. The first upgrade already required 3,000 grams of energy. This goes to show that the Tree of Heaven Punishment has outstanding potential… Wait a minute. Why does the Tree of Heaven Punishment cost more energy than the Kabbalah Tree of Life…'