is Giant Kozaky's effect a cost or can that be negated via skill drain?

It is effect, not cost.

Giant Kozaky
Dark/Fiend/4/2500/2400
If there is no face-up "Kozaky" on the field, destroy this card. If this face-up card on the field is destroyed, inflict damage to the current controller's Life Points equal to the original ATK of this card.


The first part is a Continuous Effect which can be negated with Skill Drain...

The second part cannot be negated by Skill Drain...

UDE/Netrep ruling

The effect of "Giant Kozaky" that inflicts damage to the controller activates in the Graveyard or the "removed zone", wherever "Giant Kozaky" goes to after being destroyed. "The End of Anubis" will negate the effect of "Giant Kozaky" if it was destroyed and sent to the Graveyard, but "Banisher of the Light" will not (because "Giant Kozaky" does not have to be "destroyed and sent to the Graveyard"). Nor will "Skill Drain" negate the damage if "Giant Kozaky" is destroyed.

thanks for the responces. just wondering if he was worth running in a skill drain deck. that's all i need to know.