He's is Curse of Darkness as a normal enemy, and I'm not sure what Lament of Shadow is???
Slogra's only a boss in SCV4 and Symphony.
He's easy in SotN so I won't explain, but in 4 he's a bit tougher.
So: when you whip him, move as far to the other screen from where you are, cause he's going to land on you and then try and stab you and maybe even charge at you. Then duck down and whip him. Thats probably the best advise I can give, if thats what you're talking about.