With a backstory as mechanical servitors , these cute beaked creatures do all sorts of utility things, often including providing mana
Phantasm Spiral: Game Mechanics: Normal Monster, Equip, Umi Attribute : WATER Type: Wyrm Key Card: Pacifis, the Phantasm City Feature: CDP: Heat Wave Igknight with Phantasm Spiral | CDP: Umi Two Ways, Experimenting with new DP26 Support | CDP: Multi-Umi Phantom Knight: Game Mechanics: Xyz, Link, Rank-Up Attribute : DARK Type: Warrior Key Card: The Phantom Knights of Silent Boots Feature: CDP: Appliancer Orcust with Phantom Knight | CDP: Mikanko with Phantom Knight, Burning Abyss, and Danger
His support effect is intriguing: The opponent's color changes to match your own
These sleeves minimize surface scratches and damage to your cards during storage, display, or, for gaming cards, during gameplay
As such only really combo and control decks run this
The fact that you can Special Summon a monster form the Graveyard is already powerful, so, again, conditional