When uses hex, bot try to attack other creature or face and have to recalculate to attack hex, sometimes takes no time, sometimes is long time. Same issue with sludge belcher, when is killed doesn't care about the new taunt creature.

When you have kel'thuzad on your side, sometimes don't try to keep it alive when he have to deal with big taunts and you have multiple minions to destroy it. Sometimes do it well, sometimes attack with kel'thuzad, losing it.

I didn't see the bot use holy nova.