What are rules for creatures that have a movement speed that is different than their fly speed? Say a creature has 30ft walk speed and 60ft fly speed and they walk 15 feet and take off. Does that creature have 45ft of flying movement or 30 because they used half? Believe they have 45 – it's by foot rather than proportional
— Mike Mearls (@mikemearls) October 30, 2018