Try lengths of copper pipe, I always have a copper collar around the hostas ....no slug damage....
Failing that , try road salt in an old gutter to surround the bed.
French marigolds or a bed of tagettes ( not African ) one of the best companion plants imo.
The object is to bring in the predators, they do this well and pretty to boot.
I always plant my garlic around the carrots to keep away carrot fly.
Another nice weekend spent around smelly shitholes rooting out some sport with the dogs.
The tip was full and access was limited to the fringes of the site.
On the subject of wormers, I use panacur granules for horses. You can't overdose and at £5.50 a shot
.will treat up to seven medium sized dogs.
The idea came to me via a vet years back.