text: If a creature’s power is less than 0 when it’s doubled, instead that creature gets -X/-0, where X is how much less than 0 its power is. For example, if an effect has given Grunn -7/-0 so that it’s a -2/5 creature, doubling its power and toughness gives it -2/+5, and it’s a -4/10 until end of turn.