This is not an MMORPG, but an ARPG with Coop. You can invite your friends on steam via the friends menu in the main menu. You can also set the game to "public" in the settings, and it will match you with random, level fitting players once you click play.

You can make a pure Ailment build using spells and go pure wisdom. You will cast a little slower and lack tankyness, but you will cause an immense amount of ailments. Personally, i like the stat system as it allows you to move away from class based borders.