Sky Plague Hurricane

Manny and Wendy able combine their Dragon Slayer spell to take amount of damage on their oppenents as but even that their spells are more just powerful then all other fellow Kaijudo Dragon's spells and as also here the list of Lightning and Sky spells that Manny and Wendy could combined with

List of Lightning and Sky Spells
Sky Lightning Typhoon - Manny and Wendy's Lightning and Sky spell