They are nasty early on, but once you learn their attacks you can dodge, parry, or just move out of the way relatively easily. They are weak to fire so just hit them with your torch, or lead them onto a surtling spawner if one is nearby. Fire arrows are ok, but you'll need a lot of them.

They are quite common so be ready to face a lot of them, especially if you want to build and upgrade the root set.