Hey, which class are you playing? I play with Necromancer and Sorceror, and, to fight against the Smith, I use the following tactics :
A) With Sorceror, I just use Golem as a tank, Teleport and a spell which can damage him (if you're playing at normal / nightmare difficulty, Lightning should be ok to kill him in a few seconds, otherwise, if he's immune to Lightning, Blizzard, Bone Spirit, Blood Star and Fireball should work well)
B) With Necromancer, depending on his boni, it could be more difficult, since it might happen that he has Magic immunity + Behemoth, and therefore almost impossible to kill (I wish that revived monsters will be permanent in the final MP version for this reason aswell :p). If you encounter a Behemoth + Magic Immune (or + Lightning Enchanted) Smith , just restart the game and hope that you meet him weaker next time.
If he doesn't have any of these boni, just strike him with Liightning or Bone Spirit while your skeletons and golem (an possibly revived monsters) tank him.
C?) I never played as a Rogue in Belzebub, but I'd guess that the Teleport + Shoot tactic could work. Maybe if you don't have some spells yet, you can just skip the Smith and fight him again when you're stronger.
Anyway, before activating him by approaching the Anvil of Fury, make sure that the surrounding area is completely cleared. Other monsters can prove troublesome if you're focused on hitting and fleeing from the Smith (inflicting you extra damages... blocking your path... things like these).
I hope these small suggestions will be useful to you

Happy playing!