And they deal damage directly to your opponent's life total
Discard outlets are plentiful in Modern, and six mana isnt hard to come by, especially with Eldrazi Temple and Ugins Labyrinth in the mix
Here's a partial list of other work that has to happen for any card to actually be fully implemented live on MTG Arena (not in order): A producer does a bunch of spreadsheet and database work to properly organize the cards that will be added, including choosing which version of a card will be added for cards with multiple versions
Damage prevention effects can be useful with goad and other forced-attack mechanics like the one on Bident of Thassa
Black Cat Rarity: Common TYPE: Creature SUBTYPE: Zombie Cat CMC: 2 Mana cost: USD: $0.28 EUR: 0.19 TIX: 0.03 EDHREC RANK: 14609 (1/1) When this creature dies, target opponent discards a card at random
Legendary Creature Artifact - Robot Jodah, the Unifier Legendary creatures you control get +X/+X, where X is the number of legendary creatures you control