Thunder Dragon + Mega Thunderball → Twin-headed Thunder Dragon

Thunder Dragon + Skelgon → Twin-headed Thunder Dragon

Thunder Dragon + Tyhone #2 → Twin-headed Thunder Dragon

Thunder Dragon + Lesser Dragon → Twin-headed Thunder Dragon

Thunder Dragon + B. Dragon Jungle King → Twin-headed Thunder Dragon

Thunder Dragon + Fairy Dragon → Twin-headed Thunder Dragon

Thunder Dragon + Electric Lizard → Twin-headed Thunder Dragon

Thunder Dragon + Serpent Night Dragon → Twin-headed Thunder Dragon

Thunder Dragon + Mikazukinoyaiba → Twin-headed Thunder Dragon

Thunder Dragon + Meteor Dragon → Twin-headed Thunder Dragon

Stone D. + Kaminari Attack → Twin-headed Thunder Dragon

Stone D. + Tripwire Beast → Twin-headed Thunder Dragon