[Incantation delay] delay’s the completion of an incantation. [Incantation interruption] cancels the incantation while it’s in progress. If one fuses the rabbit’s monster card with the kobold’s monster card it becomes [Incantation interruption].
[Incantation interruption] is the better skill. But if all members of a party surround a demon while using [Incantation delay] weapons, they can probably defeat it before the incantation ends. So if the combined effects of [Incantation delay] are more than a demon’s incantation casting speed then the demon might never complete it’s incantation. Other actions cannot be done while chanting an incantation. When cancelling an incantation with [incantation interruption] an attack normally follows up afterwards. If the incantation is delayed instead of cancelled then there won’t be an attack. If you keep delaying it then the attack will never happen. It’s possible that [incantation delay] is the stronger of the two.
Keep in mind that demons aren’t always on their own, and occasionally a demon will stop it’s incantation on it’s own. It’s also quite difficult to get a weapon with incantation delay for every party member. It’s best to consider other options. This is a good strategy against bosses on lower floors, but [incantation interruption] that can cancel moves becomes the better of the two as one works their way up.