Question about Combination of “Traders & Barbarians” with “Cities & Knights” Catan Event Cards + C&K - May I first play the Alchemist and then reveal an Event Card?
No. It’s either the Alchemist or an Event Card.
If all participants in a game want to agree on a different procedure, they certainly are free to do so. If, in addition to the Alchemist, you would like to reveal an event card, we recommend that after playing the Alchemist you first determine the production number, then resolve the result of the event die roll, then draw an event card (of which only the event is resolved, provided that an event is described on it), and lastly distribute the resources. Please note that this is only a variant, not the official rule.