It could also be less dramatic like flashback or targeted graveyard hate
Or, use Gontis Aether Heart to passively generate energy that goes infinite with Automated Assembly Line with a card that produces a single extra energy, like Izzet Generatorium
Today well be looking at The Ruinous Powers, a deck from the Universes Beyond product that takes place in the world of Warhammer 40,000
And then, choose "Trading Card Games" as the subcategory
There are also creature-lands like Lair of the Hydra that have an activated ability that animates them into creatures, and some planeswalkers, including Gideon-type walkers like Gideon, Ally of Zendikar and Kaito, Bane of Nightmares, that have activated abilities or triggered abilities that let them become creatures