At the main menu press Block, Auto Face, Dark Gift Menu, First Person Look, Action, Use Dark Gift, Suck Blood

Invincibility

Open the game.erg file in the Blood Omen 2 Data directory. Use notepad or a similar text editor to edit. find

"-BO2 Kain Debug Flags\kain's invulnerable"=1

and change to

"BO2 Kain Debug Flags\kain's invulnerable"=1

Now save the file and reload the game