Some cards, like Najeela, the Blade-Blossom, have a 5-color identity because of their abilities, but the card itself is only red during gameplay
Supreme King Jadens main Skill Card is Ruthless Means : once per Duel during your Main Phase, when you control an Evil HERO, you can discard a card to make one of your opponents monsters lose ATK equal to its own DEF, or lose DEF equal to its ATK
Landfall decks would do anything to get more triggers, some cards need you to sacrifice lands, and you can even use them to assemble combos like Dark Depths and Maze's End
tentacles or tendrils of red energy around whatever that yellow orb is
From then on, if I'm really struggling to get to 40 cards in order to make it playable, I call for emergency help