An interrupt or negate card must be played during the Battle Phase. Interrupt cards can only be played if the player has initiative. Initiative may be passed back to you if the character(s) being discarded, captured, or placed back in your hand put you in a situation where you are not winning. An interrupt cannot undo a prevent command if the prevent is preventing the interrupt.
‘Interrupt the battle’ interrupts all active ongoing abilities on characters and enhancements (e.g. Red Dragon), abilities that are causing you to lose the battle by removal (e.g. King Zimri), as well as the last enhancement played in the current battle if it was played by your opponent. Interrupting the battle interrupts the battle flow at the point where you played the interrupt. It does not send you back to the beginning of the battle and does not include special abilities completed prior to the interrupt being played that are no longer pending.
In most cases, an interrupt special ability must be played on a character being removed from battle, leaving no character in battle. Play the interrupt card on the character being removed from battle prior to physically removing the character. If an interrupt card cannot be played, the cards targeted for removal from battle are then physically removed.
Here is how to RESOLVE the timing issues associated with interrupt, prevent and negate cards as they are played. Put these cards in a stack (mentally if not physically) in the order they are played. The last card (top card) on the stack gets resolved first. For example, if I play card A, then you interrupt with card B, then I interrupt with card C, we resolve the actions in a ‘last on, first off’ manner. So card C’s actions are first, which in the above case would eliminate card B, so card A would be the last one standing and take effect.