Abandoned Cathedral Structure

I had came up with this idea as a way to add more mystery and life to the empty biomes like the plains. This structure would be a decent sized structure resembling a gothic cathedral. My first idea was to use this structure to implement  the necromancer mob from Minecraft Dungeons. This mob wouldn't be to speical in itself; It would be a mini-boss similar to an evoker. Perchance it could drop a tome that would allow the summoning of a new tame zombie that would fight along side you for a short period before digging back into the ground. My second idea was to add a more medieval influence, while also bringing back an old Easter egg mob. The cathedral could hold valuable loot, but this loot would be guarded by the occasional killer bunny spawn outside the church. This would likely invoke the player to imagine why the cathedral was abandoned.