When you only need one color of mana, Hall of Gemstone and Contamination are boons rather than hindrances
Akoum Alchemist's Refuge Aluren Arlinn, the Pack's Hope Azula, Cunning Usurper Blur of Heroism Borne Upon a Wind Breath of the Sleepless Captain Mar-Vell, Space-Born Cherished Hatchling Complete the Circuit Emergence Zone Final-Word Phantom Gandalf the White Gandalf, Friend of the Shire Heliod, the Warped Eclipse High Fae Trickster Hypersonic Dragon Kianne, Corrupted Memory Leyline of Anticipation Liberator, Urza's Battlethopter Mai and Zuko Najal, the Storm Runner Prophet of Kruphix Quick Sliver Quicksilver, Speedster Raff Capashen, Ship's Mage Rattlechains Renari, Merchant of Marvels Rootwater Shaman Sally Sparrow Shimmer Myr Sigarda's Aid Singer of Swift Rivers Skittering Cicada Tawnos Teferi, Time Raveler Tidal Barracuda Valley Floodcaller Vedalken Orrery Vernal Equinox Vivien, Champion of the Wilds Whirlwing Stormbrood Whirlwing Stormbrood Winding Canyons Wizards of Thay Yeva, Nature's Herald
The second ability is even better because youll be starving your opponents of mana
Dark Ritual is a must-have in a mono-black deck, as it can just sit in your hand until you're ready to use it
