Can you add new chain links during the resolution of a chain, and when are spell cards placed into the discard pile?

Ruling: You can play reaction spells in response to items on the chain before they resolve - you're adding to the current chain, not starting a new one. Spell cards go to the discard pile after they execute their instructions on resolution, and countered spells are discarded as part of being countered.

Sequence:

• Resolve the highest chain link
• Send that spell to discard
• A priority window opens, starting with the person who controls the next item on the chain (if there is a next item)
• Either a new card is played or move to resolve the next chain link
• Repeat until chain is empty

Nuances:

• If there is no next item on the chain, there is no priority window
• You can target any eligible spell on the chain for counter spells like Defy
• This interaction is particularly valuable for cards like Stupefy where you draw a card - you can play the drawn card before more items on the chain resolve