I was wondering, when the master arena ends, do you get reset to 0 trophies or 10,000? (sorry if this doesn't belong in dragon events, I thought that's the best fit)

If you are in the Master Arenas and you are higher than 10k, then you are reset back down to 10k. This is the same for the start of each season. As far as I know the only people who are reset back down to zero are hackers and cheaters or those those that have been banned either previously or currently.

@Nynaevelan Ok thanks.