Essence Crystal

Essence Crystal is an Archetype of Equip Spell Cards created by Taylor Gorrell. The Archetype is a very simple one, as they all possess almost the exact same lore:

''Equip only to a(n) *insert Type*-Type monster. When the equipped monster attacks: Increase its ATK by half its current ATK during the Battle Phase. After damage calculation: Destroy this card.''

As such, there is one Essence Crystal for each Type in the game, except Divine-Beast and Creator God. Due to how specific they are, using multiple different Essence Crystals in one Deck usually isn't a very good idea. However, "Crystal Cruncher LV4" and its evolved form "Crystal Cruncher LV8" are able to use any Essence Crystal card, so a Deck that uses them can use multiple different Essence Crystals with relative safety.