Pendrell Flux | Magic: The Gathering
Formats Pendrell Flux is Legal in
Official Oracle Text for Pendrell Flux
Enchanted creature has "At the beginning of your upkeep, sacrifice this creature unless you pay its mana cost."
Official Rulings for Pendrell Flux
10/4/2004 : You choose whether to pay or not on resolution. If not, then you sacrifice the creature. You can choose to not pay if you no longer control the creature on resolution.