You don't have to cast a spell as that ability resolves
theyre creatures that reward you for playing a dragon-themed deck, either by creating more dragons or synergizing with the ones you already have
Those arent issues that can really be addressed by simply throwing more Pikachu cards at the market and hoping for the best
Blue Rite of Replication Confiscate Negate Refute Arcanis the Omnipotent Dictate of Kruphix Finale of Revelation Harbinger of the Tides River's Rebuke Sphinx of the Final Word Tempest Djinn Voracious Greatshark Clinquant Skymage Faebloom Trick 2 Mischievous Mystic 2 Brineborn Cutthroat Essence Scatter Micromancer Mocking Sprite 2 Spectral Sailor 2 Think Twice Tolarian Terror Witness Protection Into the Roil 4 Opt Chart a Course Dive Down Flashfreeze Fog Bank Gateway Sneak Mystical Teachings Shipwreck Dowser Unsummon Rite of Replication, Confiscate, and Negate are in traditional foil
Learn more: Ed Greenwood, "Wyrms of the North: Claugiyliamatar" in Dragon Magazine 233 (September 1996) Dragons of Faern Sleeping Dragon's Wake (on D&D Beyond) Tiamat The five-headed progenitor of the chromatic dragons, Tiamat embodies the greed and vices of evil dragonkind
To compile the list, we used resale listings from TCGPlayer market prices
