Petit Dragon + Tripwire Beast → Thunder Dragon

Petit Dragon + Bolt Escargot → Thunder Dragon

Petit Dragon + Bolt Penguin → Thunder Dragon

Petit Dragon + The Immortal of Thunder → Thunder Dragon

Petit Dragon + Electric Snake → Thunder Dragon

Petit Dragon + Armed Ninja → Dragon Statue

Petit Dragon + Magical Ghost → Dragon Zombie

Petit Dragon + Sea Kamen → Spike Seadra

Petit Dragon + Ameba → Spike Seadra

Petit Dragon + Rainbow Flower → B. Dragon Jungle King

Petit Dragon + Barrel Lily → B. Dragon Jungle King

Petit Dragon + Needle Ball → Koumori Dragon