Getting a two-mana tapping rock isn't why it's here or heavily played though
(The earliest example would be Gauntlet of Might, but this shows the design technology being used more readily.) Artifacts would go on to care about specific colors to remain narrow, a great tool in the box
One such recent card, which ended up being a haymaker in Standard, is Archfiend of the Dross
This style of Energy promo is incredibly popular, and there were different Pokemon silhouettes chosen for each energy, with Ampharos covering Lightning, Ho-Oh for Fire, and Umbreon representing the Darkness Energy
GR Gold Rare Limited Limited Set Rotation X SPELL Quick-Play Set 2 Field Spells with different names from your Deck on the field (1 on your field, and 1 on your opponent's field)
You can obtain the Wallace (2-Stars rarity) card by opening Everyday Wonders from Everyday Wonders set