@dSKyNafinchin Yep, exactly. Cooperate with 3 other humans playing other pilots, survive 5 waves. At lower difficulties, you get some 're-dos' when you fail a wave. At higher, no re-dos (I think, not actually gone above Medium yet) and the AI gets more aggressive.
Side note - I am terrified how they define "more agressive" when I have been brutally hunted down by a Titan with a flamethrower just on medium across half the map...
Like I keep saying, I really wish they would add something like Frontier Defense to Apex so I could stop ruining all your all games in BR...