So if this was played against a Paladin who had a lone Tirion on the board, would it destroy the Ashbringer?
It does not. Things happen one after the other, but the one thing that never happens during a card resolution or trigger is minions dying. For example, if you have 3 Wild Pyromancers, and play a spell, they ALL get to trigger (even though they are all at 0 Health after the 2nd one triggers). We always wait for all effects to finish firing before cleaning up minions who are "dead". In this case, Sabotage kills Tirion, but he doesn't actually die until the entire effect finishes, at which point his Deathrattle will fire.
The only exception to this rule is Poison Seeds, which kills things during its resolution in order to make room for the treants. I hope that's helpful - we're always trying to find ways to make the underlying rules more clear, but this is a case where it isn't super intuitive.
Ben Brode
It does not. Things happen one after the other, but the one thing that never happens during a card resolution or trigger is minions dying. For example, if you have 3 Wild Pyromancers, and play a spell, they ALL get to trigger (even though they are all at 0 Health after the 2nd one triggers). We always wait for all effects to finish firing before cleaning up minions who are "dead". In this case, Sabotage kills Tirion, but he doesn't actually die until the entire effect finishes, at which point his Deathrattle will fire.
The only exception to this rule is Poison Seeds, which kills things during its resolution in order to make room for the treants. I hope that's helpful - we're always trying to find ways to make the underlying rules more clear, but this is a case where it isn't super intuitive.
Ben Brode
it does :)