You don't lose unspent red mana as steps and phases end.
Magecraft — Whenever you cast or copy an instant or sorcery spell, discard a card, then draw a card. If this is the second time this ability has resolved this turn, Ashling, Flame Dancer deals 2 damage to each opponent and each creature they control. If it's the third time, add RRRR.
Non Foil / Near Mint - $5.88
Non Foil / Slightly Played - $5.29
Non Foil / Moderately Played - $4.70
Non Foil / Heavily Played - $3.53
Non Foil / Damaged - $2.94