You don't know "toxic" until you've played a MOBA.

I've gotten some impatient groups with DF, but generally I find that if you try to establish a friendly atmosphere early on by discussing the strategy and having a laugh or two before things get serious, the "Greater Internet F***wad Theory" starts to break down a bit. This is not always the case, but pulling out your keyboard and reminding everyone that there's a real person behind the avatar greatly increases your chances of having a good time.