Most Rograkh/Kediss decks work in roughly the same way: play Rograkh on turn 1, buff it up on turn 2 with a Dragon's Mantle-adjacent effect, drop Kediss on turn 3, and then dump all your mana into buffing Rograkhs attacks
Specifically, he mentioned how they provided room for Wizards to properly explore Zombie and Energy themes without bloating the main set
Some decks even use the graveyard to your advantage, letting you play powerful cards out of it after they've been discarded
Being creatures comes with downsides, but these pack your deck with enough explosive, synergistic potential to run anyway
With both sides potentially having a mana cost, it's more important to keep track of the icon in the top left
This simple effect is most powerful when paired with cards that can search for Energy Search directly, like Irida or Arven