With a glowing shield, Marius stands up and steps through the bushes. He stops there, soon acompanied by Taz. Grindylows do not take the invitation, they instead hastly retreat towards the sea.

Spoiler
Show
In one round, they are 115 feet from the camp (100 feet from Taz and Marius), which is only obvious to those with low-light vision. If you don't chase right away, consider them to have retreated.