* Soul Drain's effect: Soul Drain negates the activation of monster effects that target a face-up monster on the field. It does not prevent effects that trigger based on a monster's presence or position on the field.
* Dark World monster effects: Many Dark World monsters have effects that trigger based on their summoning conditions, position on the field, or specific actions like being destroyed. These effects are not directly "activated" by the player, so Soul Drain does not affect them.
Examples:
* Gravekeeper's Spy: Its effect to Special Summon itself from the graveyard when another Dark World monster is destroyed is not an activated effect, so Soul Drain has no effect.
* Dark World Dealings: Its effect to Special Summon a Dark World monster from the deck when a Dark World monster is sent to the graveyard is not an activated effect, so Soul Drain has no effect.
However, Soul Drain can negate some Dark World effects:
* Dark World monsters with effects that target: Some Dark World monsters have effects that target, such as "Dark World Lightning" targeting a monster for destruction. Soul Drain can negate the activation of these targeted effects.
In conclusion: Soul Drain does not negate most Dark World effects, but it can negate specific effects that target.