Cannot be Normal Summoned/Set. Must be Special Summoned (from your hand or Graveyard) by banishing 3 EARTH monsters from your hand and/or Graveyard, and cannot be Special Summoned by other ways. Rock-Type monsters you control cannot be destroyed, except by battle. If this card is sent from the field to the Graveyard: You can add up to 3 Rock-Type monsters from your Deck to your hand, whose total Levels equal 8. You can only use this effect of "Block Dragon" once per turn.
Based on the box it was released in, it is implied that Block Dragon was meant to be used alongside Magnet Warriors, more specifically Electromagnet Warriors. Electromagnet Warriors’ ability to tribute themselves and search out other Magnet Warriors lets you fill the graveyard to fuel Block Dragon’s summoning cost.
Gem-Knight monsters used as fusion materials in your graveyard can be reused as cost for Block Dragon’s summoning. Block Dragon can in turn search out more Gem-Knights to use as fusion material when he leaves the field.
You can form a Rock themed deck with the Rock-type Koa’ki Meiru monsters. In this case Block Dragon can prevent them from destroying themselves when you cannot provide their maintenance cost.
Use Release from Stone to revive the monsters you banished as cost during Block Dragon’s summoning.
|Actions||Activates from your Graveyard / Adds from Deck to hand|
|Banished categories||Banishes from your hand / Banishes from your Graveyard|
|Monster/Spell/Trap categories||Cannot be destroyed by card effects|
|Summoning categories||Cannot Normal Summon / Cannot Set / Special Summons itself from your hand / Special Summons itself from your Graveyard / Nomi|