Salut skydius 🙂

La différence entre Stardust Dragon et Snowman Eater est simplement liée au fait que pour Stardust, activer son effet est un coût (Fast Effect – sacrifice pour annuler un effet de destruction sur le terrain + Trigger Effect – invoc spé en End Phase) alors que pour Snowman, c'est un effet déclencheur (trigger effect) qui s'active lorsqu'il est retouné face recto.

Vu que pour Snowman, c'est un effet qui s'active obligatoirement sur le terrain, Skill Drain fonctionne sur lui alors que Stardust, ses effets fonctionnent dans le cimetière même si il possède lui aussi des trigger effects + un fast effect que Skill Drain ne peut annuler puisque ça se passe dans le cimetière ;).

Rulings officiels Snowman Eater

TCG Rulings :

“Snowman Eater’s” effect targets. http://shriektcg.twoday.net/stories/5677777/

OCG Rulings :

This effect targets one face-up monster on the field. http://yugioh.faq.konami.jp/EokpControl?&lang=en&tid=47389&event=FE0006

This monster is not a Flip Effect Monster. http://yugioh.faq.konami.jp/EokpControl?&lang=en&tid=47389&event=FE0006

Rulings officiels Skill Drain : http://yugioh.wikia.com/wiki/Card_Rulings:Skill_Drain

On the Monster Leaving the Field

The effect of "Skill Drain" negates the effects of Effect Monsters that are face-up on the field. Thus, it cannot negate the effect of a monster if the monster is in the Graveyard when the monster's activated effect is resolving. "Exiled Force" and "Rescue Cat" Tributes itself or sends itself to the Graveyard as activation costs for their effects, so the monsters are in the Graveyard when their effects resolve. Thus, "Skill Drain" cannot negate their effects, so you will destroy the monster or Special Summon the Beast-Type monsters from your Deck.

Number 30: Acid Golem of Destruction:

The effect "During each of your Standby Phases: Detach 1 Xyz Material from this card, OR take 2000 damage." can be negated by "Skill Drain". However, if "Skill Drain" is active and "Compulsory Evacuation Device" is Chained to the effect of "Number 30: Acid Golem of Destruction" during the Standby Phase, then "Number 30: Acid Golem of Destruction" is no longer on the field, so "Skill Drain" cannot negate its effect. "Number 30: Acid Golem of Destruction" is no longer on the field, so you cannot detach an Xyz Material from it, so you take 2000 damage.

Stardust Dragon :

"Skill Drain" has no effect on "Stardust Dragon". For the first effect, Tributing "Stardust Dragon" is a cost, so "Stardust Dragon" is not on the field and is unaffected by "Skill Drain". The second effect activates in the Graveyard, so "Skill Drain" cannot negate it.

Cela devrait t'aider à y voir plus clair (en espérant que tu ne sois pas allergique à l'anglais 😆 )