So, on FTB as I sought out Nether Stars, and thus went to Nac's place to summon the Wither Boss in a safe environment, we were talking about the Wither on the Vanilla. And I thought about two options available to us. 1. We only ever summon the Wither in the Nether, and a decent distance from any portals. 2. We set up a Wither Summoning Post. A Building of bedrock, solely, dedicated to summoning the wither in a safe environment, so nothing gets hurt, except the player trying to kill the wither. Obviously, both would be acceptable. But option 2 would require an administrator of the Vanilla server to do.
Only if you build it as an arena with seating so we can spectate other players getting their asses kicked.