Just a quick heads up that Headmaster Kel’Thuzad’s Spellburst interaction is currently bugged when interacting with Professor Slate, or maybe Poisonous spells in general.
Not only do minions killed by Poisonous spells not summon on your side of the field, but even if the spell dealt enough damage to normally kill the minion Kel’Thuzad’s spellburst interaction is overridden by the bugged Poisonous one.
Tested this in practice mode and took screenshots: