It is recommended for all people who only just started to play duel links but at least one structure deck. But aside from that, people who want to build E-Hero themed decks are recommended to buy this Box.
If this card is Normal or Special Summoned: You can add 1 "Polymerization" from your Deck to your hand. During your Main Phase: You can activate this effect; you cannot Special Summon monsters for the rest of this turn, except Fusion Monsters, also send 1 "Elemental HERO" monster from your Deck to the Graveyard, except "Elemental HERO Blazeman", and if you do, this card's Attribute, ATK, and DEF each become the same as the monster sent to the Graveyard, until the end of this turn. You can only use 1 "Elemental HERO Blazeman" effect per turn, and only once that turn.
When this card is destroyed by battle and sent to the Graveyard: You can banish this card and 3 "Elemental HERO" Monster Cards with different names from your Graveyard to target 1 Normal Spell Card in your Graveyard; add that target to your hand.
"Elemental HERO Heat" + "Elemental HERO Lady Heat" Must be Fusion Summoned and cannot be Special Summoned by other ways. If this card battles a WATER monster, this card gains 1000 ATK during the Damage Step only.
When an opponent's monster declares an attack: Your opponent chooses 1 random card from your hand, then if it is a monster that can be Special Summoned, Special Summon it. Otherwise, send it to the Graveyard.
They're weak on their own. Their potential can be seen on fusion monsters not the fusion material itself (except Blazeman and Stratos). And GX world barely started, so it's expected that there will be events/main boxes that will add support to Heroes.
indeed with everyone. the structure deck is bad. But the following are key cards for E-hero fusion.