I won't call this a combo as I'm not sure it really is one. It is just 3 cards I have found to be very synergistic.
{Geth, Lord of the Vault} + {Trepanation Blade} + {Mindcrank}
Basically feeds Geth great fodder for his ability, plus the bonuses, as well as killing morale of opponent watching so many cards go away and u snagging any good creatures that you want...and making them lose even more.