So, this is a Wyrm Ritual Monster, which is pretty unique, that has a powerful protection effect, if you use 3 monsters, and a very powerful effect that activates when a monster is Special Summon and negates its effect, and is able to reduce your opponent's other monsters' ATK and if they become 0, they are destroyed. The Ritual Spell is the standard fair, but also can be added back to your hand, along with another monster from your GY during your Standby Phase, should you control only Supremacy Dragon.
You can Ritual Summon this card with “Supremacy Ritual”. If this card is Ritual Summoned by Tributing 3 or more monsters, it cannot be targeted or destroyed by your opponent’s card effects. Once per turn, when your opponent Special Summons a monster(s): You can target 1 those monsters; negate that target’s effects, then all other monsters your opponent control lose ATK equal to that target’s original ATK, then if their ATK has been reduced to 0 as a result, destroy those monsters
This card can be used to Ritual Summon “Supremacy Dragon”. You must also Tribute monsters from your hand or field, whose total Levels equal 10 or more. If the only monster you control is “Supremacy Dragon”, during your Standby Phase: You can return this card and 1 monster from your GY to your hand. You can only use each effect of “Supremacy Ritual” once per turn.