Besides community-made formats like PreFIRE, Classic Legacy, and 2015 Modern, one way I like to play with uncompetitive cards and strategies is through Spice Paradise, the Premodern webcam league I organize that prohibits top tier strategies
Collectible card games are the only hobby where you can pay thousands of dollars for cardboard and little else
Because the effect of the spell will change depending on whether or not a Gift was given
In fact, Primeval Titan has been the face behind some of the most degenerate decks in Modern, starting with the Cloudpost deck that was prevalent in the initial days of the format, to the Red-Green Valakut deck, and then the Amulet Titan deck both in its degenerate form with Summer Bloom, and the more toned down version we see today with Dryad of the Ilysian Grove and Urzas Saga
The card is exceptionally slow, but in decks that care about +1/+1 counters, this will create a lot of value