Hello!
If you are still having this problem, (and for anybody else who might have it), there is a solution!
The Entity ID for an entity in orespawn conflicts with the entity ID for the golem, part of BattleTowers
What you need to do is find the BattleTowers config in your modpack folder and open it with Notepad, or similar.
Change the value of "Golem Entity ID" (originally 186) to 296 (an open entity ID)
If this did not work, there are other mods that are conflicting with entity ID 186 or 296. All I can say to that is keep trying until you have an open entityID number. It SHOULD be fine!! Hope this helped
Drew