Spike Seadra + Kanikabuto → Kairyu-shin

Spike Seadra + Zarigun → Kairyu-shin

Spike Seadra + Destroyer Golem → Stone D.

Spike Seadra + Barrel Rock → Stone D.

Spike Seadra + Minomushi Warrior → Stone D.

Spike Seadra + Stone Ghost → Stone D.

Spike Seadra + Kaminari Attack → Twin-headed Thunder Dragon

Spike Seadra + Tripwire Beast → Twin-headed Thunder Dragon

Spike Seadra + Bolt Escargot → Twin-headed Thunder Dragon

Spike Seadra + Bolt Penguin → Twin-headed Thunder Dragon

Spike Seadra + The Immortal of Thunder → Twin-headed Thunder Dragon

Spike Seadra + Electric Snake → Twin-headed Thunder Dragon