It's 561 over 12*11*30*6545 what is approximately 0.0021645% of chance IF there's exactly 1 Curious Glimmerroot and 1 Mass Dispel in Priest's deck, and 1 Primordial Glyph in Mage's deck at the start of the game. It's pretty low I guess.
I found lethal with thalnos and zealot: Trade every minion with their counterpart (only exception is 8/7) Then Thalnos and Zealot with defile and finally mortal coil against the last taunt and your 8/1 can hit face. It is very awesome that they are so many different possibilities to get through the taunts! /Edit: Wow! If you trade like I said you don't even need Thalnos and Zealot at all ^^
i guess defile's spell damage interaction isn't wrong because the game technically resolves the death of the spell+ minion after the first casting... whereas fatigue damage with coldlight oracle will still damage bolf ramshield even if it has negative health after the first fatigue "card" is drawn but not the second.
6:00 There was another way. Same start, but instead of playing the spell power just coil a 3 health minion. Then you have minions with 1, 2 ,3, 4, 5, no 6 and yours at 7 health. Defile still clears all but the 8/7 and you win.