Or you could take it even further with cards like Etali, Primal Storm that use combat to cast spells
Sin, Spira's Punishment Rarity: Rare TYPE: Legendary Creature SUBTYPE: Leviathan Avatar CMC: 7 Mana cost: USD: $0.33 EUR: 0.26 TIX: 0.02 EDHREC RANK: 9638 (7/7) Flying Whenever Sin enters or attacks, exile a permanent card from your graveyard at random, then create a tapped token that's a copy of that card
Intentional draws: In the final round of Swiss when both players are mathematically locked into either making cut or missing cut regardless of the round result, an intentional draw (ID) is legal and common in tournament play
The slots don't go all the way to the bottom to help prevent cards getting pinched or bending
Stamina recharges over time, but you can also earn or use saved Event Hourglasses to jump back into battles faster
Alternatively, they could keep their Earth attribute while getting an erratum that specifies they are also Metal or Wood, so as not to change their effects if they involve Earth attribute monsters in some way