I've seen this building on others accounts. How do I get the Tavern & what does it even do? Thank you for any info.

Hi
Tavern and monster arena are just a decoration now and they are not available in shop
Tavern & arena were to encourage players to invite others to game ,tavern was offering 3 monsters as shown below as a reward . arena was offering extra pvp point --from 2 to 3 --

Ok then, thank you!