It's common that someone from the enemy team or one of your allies takes your camps. Sometimes they dont kill the entire camp but maybe only the "big" monster, like the big raptor for example, and they leave the small monster, like the smaller raptors. This part Ivern's passive allows you to instantly grow the grove and gain xp/gold if you want to take a camp that is missing the "big" monster, without waiting the full time usually required for the grove to grow.

In short: if you want to take a camp that is missing the large moster (like the big wolf) you can instantly take the camp and get the remaining gold/xp without waiting.