While some Elemental HERO monsters are pretty weak, they're often worth keeping around for the Fusion Monsters they merge together to form such as Elemental HERO Flame Wingman, Elemental HERO Neos Knight and much more and a lot of these Fusion Monsters have pretty powerful effects so they're pretty daunting to deal with once they hit the field
Dark Cavalry, which can typically be Special Summoned from the Extra Deck with the Eye of Timaeus, can be used as both a high-ATK beater, as well as a negate machine
As sets go, this is a fairly small expansion, with 94 regular cards included , but that also makes completing the set more achievable - a genuine boon for collectors like me, who get a kick from adding an expansion's full roster to our binders
Once per turn: You can detach 1 Xyz Material from this card, then target 1 face-up Special Summoned monster your opponent controls
However, you can play a few as late-game options
Victini from White Flare and Larvesta from Black Bolt are both standouts