Warhammer 40K: Chaos Gate

I’ve been playing quite a bit of Chaos Gate lately (whenever I find the time that is), and I realised I can’t beat the final boss. I blitzed through the game recycling a squad of four marines, never levelled up anybody else, and I don’t have any mid-game saves. Which means in order to complete the game, I need to go back and start again, something I really don’t have the patience for. These days we have youtube of course, so here’s the ending (spoilers…)