Thanks for the second photo - it looks like the brown leaves in this image are not showing slug damage but instead a leaf blight caused by a fungal infection. This happens most often due to poor drainage, poor air circulation and warm, humid weather. Try to avoid wetting the foliage. Cut back and brown leaves so the plant can have a fresh start. Are there white webs on those leaves? That could mean an infestation of spider mite. Spider mites cause damage when plants dry out in hot weather. So slugs on the hosta and fungus on the groundcover. Don't panic, treat the slugs with slug bait then cut back the groundcover, add a fresh layer of mulch and see if it grows back healthy. Keep growing, Marianne Binetti