"Hex-Sealed Fusion", known as "Fusion Seal Organism" ( 融 ( ゆう ) 合 ( ごう ) 呪 ( じゅ ) 印 ( いん ) 生 ( せい ) 物 ( ぶつ ) , Yūgō Juin Seibutsu) in the Japanese version, is a series of Rock monsters that have the same two effects which support Fusion Monsters.

The two effects are as follows:

Mechanics

When resolving the second effect, the "Hex-Sealed Fusion" monster can be treated as a Fusion Substitute Monster with its first effect.

Special Summoning a Fusion Monster with the second effect of this monster does not "properly" Special Summon the Fusion Monster, so it cannot be Special Summoned from the Graveyard or while banished (unless it it returned to the Extra Deck and then Fusion Summoned).