Possible Duplicate:
What kind of a team setup is required to kill Roshan before the match begins?
A friend and myself recently nailed down how to duo Roshan at level 1 using Ursa (with fury swipes) and Skeleton King (with vampiric aura). I've also witnessed an Ursa (fury swipes) and Lich (frost armor) managing to take down Roshan before the game started.
What other two hero/ability combinations can consistently kill Roshan as soon as the game begins?