I don't think the cooldown should apply for guild brawls. Also there should be a new locking system that can be applied to cards, where players can rule certain cards not to be used in survival mode in order for them to be able to protect their brawls(if this is not changed), ranked and tournament core teams that they don't want to risk.
I would be happy to try this with by secondary teams and lower level cards, but I would hate to accidentally use some of my core cards and potentially ruin brawls for my guild or my normal ranked season.
Such locking option is a must imo, otherwise the stress to not accidentally pick core cards would be too much and I would not deem the risk worth it. Also those core cards in current system will block you from selecting you lower level cards, which the locking system would solve as they would not be visible in the selection screen.
I hope I'm making any sense, just woke up.
The ability to lock your cards from being used in survival/hardcore is an option i suppose.
I wonder if we could coordinate between peakmonsters and allow them to use lists to see which cards the user has in a list (a do not use in survival list). Or they can do their own list like system. it's not that complicated took us very little time.
It is how Splinterlands can sell new potion :)