EPTI did air on brutal, and nydus on hard (though I can't imagine nydus on brutal being too different... snipe the nydus, tanks piled in the middle, PF or lots of flame turrets around everything, SCV's scattered to repair slight damage, etc. etc. etc.)
I tried out air on brutal to attempt to do the mind control method, thinking it'd be good for shits and giggles. For some reason, I had incredible trouble getting it done right. Kept getting overrun, not having enough towers, or ground defense, despite having a few tanks and turrets still (obviously not as much, need to keep up lots of MC towers).
Then I just tried it with no gimmick (I had bought all the air upgrades). Massed vikings (40+ at the end), banshees (15 or so), and SV's (5). Killed the leviathan no trouble, lost like 2 vikings, and the rest seemed really REALLY basic.
Still wish I could get the MC method down for shits and giggles though
But ohh well, overall was disappointed with how easy it was (brutal air without gimmick) given everyone screaming blue murder about it.
