Hint

If you choose to not let them die, they can still die due to running into the monster while out and about.

For the first monster, keep an eye of for their horn

For the second, keep an eye out for tendrils

For the third, keep an eye out for their horn (as well)

For the fourth, keep an eye out for the gradient. I did make it too subtle, but did have the gradient behind the foremost trees, soo if a foremost tree is brighter than the area behind it, it is in a darker area and avoid that direction