You can play at sorcery speed and hold up one mana
Scientists Aang and La, Ocean's Fury Aatchik, Emerald Radian Abandoned Air Temple Abigale, Poet Laureate Abomination, Terrifying Titan Action News Crew Adaptive Gemguard Additive Evolution Adorned Crocodile Adrenaline Jockey Adventurous Eater Aegis Sculptor Aerith Gainsborough Aerith Rescue Mission Agatha's Soul Cauldron Agent Bishop, Man in Black Agent Maria Hill Agent Phil Coulson Aggressive Negotiations Ainok Wayfarer Ajani's Pridemate Ajani, Caller of the Pride Alesha, Who Laughs at Fate Alessos and Pras, Acrobats Alien Invasion Amalia Benavides Aguirre Ambitious Augmenter Anim Pakal, Thousandth Moon Ant-Man, Colony Commander Antiquities on the Loose Arala, Hedron Scaler Araa, Heart of the Spider Archdruid's Charm Armasaur Guide Ascendant Dustspeaker Ash, Party Crasher Ashiok, Wicked Manipulator Astrologian's Planisphere Atlantean Cavalry Atmospheric Greenhouse Attuned Hunter Aunt May Avatar Enthusiasts Azula Always Lies Badgermole Cub Bagel and Schmear Bahamut, Warden of Light Banner of Kinship Baron Strucker, HYDRA Overlord Barrensteppe Siege Bartolom del Presidio Bat Colony Beetle, Legacy Criminal Beetle-Headed Merchants Berta, Wise Extrapolator Bile-Vial Boggart Bioengineered Future Biosynthic Burst Black Widow, Super Spy Blacksnag Buzzard Blazing Bomb Blech, Loafing Pest Blood Hustler Boar-q-pine Boggart Mischief Bogslither's Embrace Bold Biochemist Boneyard Desecrator Boommobile Bounding Felidar
Ruthless Ripper is a neat one from Khans of Tarkir that can morph face up without mana, so it makes sense the design of disguise keeps room to grow
For example, if two lands entered the battlefield under your control this turn before Bioengineered Future entered, creatures you control will enter with two +1/+1 counters on them this turn
