A fully upgraded Cyro Bomb will kill your Engineers and freeze your Scarab, followed up by a 4x MAC Blast. Coordination with leader powers will take this down, as well as 3 Spartan Cobras (God help you if they are 13 stars, they take down Scarabs in 2-3 shots.) and a pop full of Wolverines.
[URL=http://www.bungie.net/stats/halo3/default.aspx?player=Gen+C4B0053][IMG]http://www.bungie.net/card/halo3/Gen+C4B0053.ashx[/IMG][/URL]