Wizard with a Gun adds 4 player co-op to its action crafting mix, and it's free to try for the weekend
There are plenty of survival crafting action sandbox games, but only one of them is purely focused on the concept of being a wizard with a gun*. That's the aptly-named Wizard with a Gun, which got an upgrade to four-player co-op this past week in its new Better Together update and so I guess they'll have to rename it to Wizard with a Gun and Several More Friends.