Patagia Viper

Two enters-the-battlefield triggers, both firing at once with their controller choosing the order, do all the work here. The first makes a pair of 1/1 ground Snakes no matter how the spell was cast; the second checks whether blue mana paid for any part of the casting and, if it did not, sacrifices the flier on the spot. Cast it for its printed four mana off green alone and you keep the two tokens but watch the 2/1 walk out the door immediately; spend blue somewhere in the cost and the sacrifice clause resolves without doing anything, leaving the flier to shepherd its brood. That split is what makes the green-only mode a genuine choice rather than a dead card: the value floor (two ground Snakes for four mana) is honest, and the upside (a flier on top) is the reward for reaching into the second color. The design belongs to an era when hybrid and gold cards were constantly nudging mono-color decks toward splashing. What gives the conditional sacrifice teeth is its exact wording: the check is for blue spent during casting, so any blink or reanimation effect that returns the Viper to the battlefield without re-paying that cost triggers the sacrifice every single time. The Snakes always survive each pass; the body only sticks if you committed to blue on the way in.