Double Tuning (also known in some circles as Overtuning) is another method of Summoning Synchro Monsters; as the name suggests, two Tuner monsters are used, rather than the usual one. This type of Synchro Summoning was first seen in Episode 113, used by Jack Atlas when he summoned Red Nova Dragon.
Though "Red Nova Dragon" is the first to specifically say that it needs 2 Tuner monsters, double tuning is first possible with XX-Saber Gottoms when the EARTH-Attribute monster(s) used is also a Tuner monster; however, Gottoms can be Summoned with any number of Tuner monsters, provided they are EARTH. Also, almost every Synchro Monster could be theoretically Doubled Tuned with Phantom Lord Hide Ride, who can be used with more than 1 Tuner monster to Synchro Summon.
So far, the only monsters that require this method of Summoning are:
|Red Nova Dragon||スカーレッド・ノヴァ・ドラゴン||12||DARK||Dragon||3,500||3,000|