Instant, 2UUG (5)
Rare
Counter target spell. Put an X/X green Ooze creature token onto the battlefield, where X is that spell's converted mana cost.
"The Simic can grow anything out of a puddle of sludge. I just hope they never join forces with the Golgari."
—Teysa Karlov, Grand Envoy of Orzhov
Illus. Mike Bierek

1/24/2013: If the target spell is an illegal target when Mystic Genesis tries to resolve, Mystic Genesis will be countered and none of its effects will happen. You won’t get an Ooze token.
1/24/2013: You may target a spell that can’t be countered. When Mystic Genesis resolves, the target spell will be unaffected, but you’ll still get an Ooze token.
Legal in Vintage (Type 1)
Legal in Legacy (Type 1.5)
Legal in Extended (Type 1.X)
Legal in Standard (Type 2)
Legal in Classic (MTGO)
Legal in Commander
Legal in Modern