Can reactions be played right after the last card on the stack resolves?

Ruling: No, you cannot play reactions after the last card on the stack resolves. If the last item on the chain resolving doesn't cause an item to go on the chain, the chain closes immediately afterward.

Nuances:

• During a showdown, you can play reactions after cards resolve because the showdown keeps the chain open
• Reactions must be played during the stack, not after it fully resolves