how to beat The Groom terraria

Answer 1

He doesn't spawn without hacking. Check my guide here: http://nerd-age.com/?p=755

He's not very strong, according to his mined stats. When he gets fixed it should be easy.

Answer 2

He spawns without hacking anything ... you need 1.0.5 and you need a "Blood Mood" night. With a bit of luck, he will spawn somewhere ;)