Nevermind the insane bonuses from holding the Emperiums. Nevermind Half-Life and Heartbreaker. Nevermind the dozen other fixes the map needs.
The two biggest things turning people away from WoE are the BP penalty and the arguably overtuned siege weapons. I don't know what you intend to accomplish with the test season, but when no one is joining WoE, you're not getting any testing done.
At the very least, remove the BP penalty for the duration of the TEST SEASON so people can enter without worrying about being farmed for their hard earned points earned from Colosseum. If you have to, further reduce BP gains from killing other players -- again so players can feel like they're not wasting their time and armour durability for nothing. As for the siege weapons, Collision has already offered not to use them and that didn't do anything, so the culprit seems to be the BP losses.
Just like with the bug fixes, if you want something done, you need to act now instead of trying to wait it out until the end of the season. It may already be too late but it's worth a try. Remove the BP penalty. It's clearly within your power. Do it.