pokemon gx rainbow rare cards Metagross 157/145 Guardians Rising Secret Card Evolves from Cosmoem Type Necrozma Gx 153/147 Burning Shadows

You may tap a creature you control to reduce that cost by an amount of generic mana equal to its power

Here's more photos of the cards I snapped:

While this won't allow you to cheat out too many hard hitters, you should be able to secure some great defenders or creatures that are costly thanks to their abilities

It also allows you to skip your upkeep, which can be huge against certain strategies used in EDH

(In early 2023, when CGC integrated their sports and TCG grading under one umbrella, they introduced a refreshed label design, but the changes are subtle.) The important part is the info is clear and easy to read

You can cast a creature with the mutate keyword for an alternate mutate cost, provided you already control a creature