The baseline effect is good, you get your mana back, but in EDH this can easily become a game-winning play
Kumena requires you to run untappers to get full value while Hakbal doesn't need that
Plus, the whole point of the Custom Card Contest in the first place is to have fun while making cards
The infinite combo between these two cards comes about thanks to their synergistic cantrips
Sure, you have to deal combat damage with a Dino to pay the prowl cost, but Dinosaurs are all about attacking, so that should be a trivial feat to achieve
With the latest set, WILDS UNKNOWN , finally achieving a simultaneous release with the English edition, theres never been a better time to jump into the Japanese market