Sanity.bsp by Bal.
The most fucking awesome 12-16 player Clan Arena map this side of q1edge.
I'm sure he didn't make it with Clan Arena in mind, but for a rowdy game with lots of players, Sanity was incredible for Clan Arena especially with the circular design and paths.
What was Clan Arena? It was Last Man Standing with teams (Red Vs. Blue). With 12-16 players it was blissful chaos.
short YouTube video
AFAIK: Bal mostly made deathmatch maps.