The artifacts or creatures you untap could be used for waterbending, but my mind can't help but wander to the rocks, dorks, and cards with the best activated abilities as targets to untap
While not as good (and very much looking like an End-Raze Forerunners rip off), it's still another sudo copy of the effect
One Piece has followed this trend closely, with competition-based rewards consistently outperforming standard pack-pulled cards in both price stability and rarity
The prevalence extends to Commander, with a ton of cards released that help bolster up the archetype in that format
With four main sets released in the year, Into the Inklands, Ursulas Return, Shimmering Skies, and Azurite Sea, there are a lot of cool cards for collectors
If that last idea interests you, then let us introduce you to the wheel deck