But actually ragular Crystalline Caves are good, there is just a valid reason why people don't like to go there and to other battlefields, and the reason is - because they can get chess sets with less efforts (less time, and less gold spent for blessings, wraiths etc.), especially healers and locksmiths, because they need antitrauma bonus, not trauma that arsenal armor has.
There was time, when arsenal armor was the best armor, and people wanted to get it, and it requires valor rank, so people were going to battlefields. Now we have chess sets, and quests for purple armor. Both pretty easy tp get.
Remove chess sets and purple armor from the game, make blue transferable armor like Barbarian set pieces very rarely drop from monsters, and people will go to battlefields again.
And make new valor quests for crystalline caves, for example 12 wins in row, 400 spheres, 226 green crystals, and 20 red arena badges. Or some quests like that.
People who have purple armor will argue with me, I don't doubt about that, but let me calm them down - most of them are valor players, and have good ranks, so if purple armor and chess sets are removed from the game - their blue arsenal armor will be still the best armor.
If you don't understand the idea - give people choice to get green armor or arsenal armor, they will choose arsenal armor obviously (Just make new arsenal armor with antitrauma bonus for locksmiths and healers).