Are these yugioh card discard effects costs?

Question

My brother collects a dark world deck and he wants to know if it's a cost when you discard due to the effect of these cards:

gray wing

snipe hunter

dark crusader

non-aggression area

Answer 1

Yes, they are costs.

The cards you have listed have Ignition effects. Discarding a card for them is the cost.

Answer 2

yes. those are all costs

You could, however, use cards like:

Dark World Dealings

Dark World Lightning

Card Destruction

Morphing Jar

Brron, Mad King of Dark World

The Cheerful Coffin

Fine

Answer 3

snipe hunter doesn't work i have a yugioh WC