Zhao Kai’s In Action

Prior to the monster wave's appearance, Xu Feng had made sure to cast Verdant Collapse all across the field. 

To ensure it would be on time and within the summoned duration, he made sure to calculate everything. This included wasting many precious potions to shorten the cooldown and mana usage. 

With his micro-movement and action, he effectively planted over 70 plants. 

Although not all of it was discovered and managed to be in use, just the fact that he manipulated and caused the Colossus to destroy 15 plants was already an ideal amount. 

With 15 plants damaged and killed by them, Xu Feng could now stack on the effect and target the Colossus. 

The moment it locked onto the Colossus, it was equivalent to weakening a boss-type monster into a common mob-type monster. A mob type where one continuously kills to earn some experience points.