This is the Purple Coldlight Combo Mill Warrior Deck Nov 16 he was playing in the top 10 legend early on in the season.
It’s an interesting deck that has several win conditions. But the main combo in the deck uses fatigue to kill your opponent.
When you use Brann Bronzebeard + Coldlight Oracle you and your opponent draws 4 cards. If you use both Coldlight Oracles that’s 8 cards each. If you enter fatigue as you pull all these cards that’s more than 60 damage!
So how do you not die at the same time? Violet Illusionist. You’re immune to all damage while you have this card in play. So, you can use this minion on board while clearing up minions with Fool’s Bane, and if you need to be immune while drawing you can play her out.
This is why Emperor Thaurissan is in the deck. Ideally you want to get an activation on all of these key cards to make this combo easier to play. Don’t be afraid to use it just to burn some of your opponents cards during the game too if they are holding a big hand.