name: Thundering Mightmare
originalText: {T}: Add one mana of any color. When you next cast an artifact spell this turn, that spell gains sunburst. (If it's a creature, it enters with a +1/+1 counter on it for each color of mana spent to cast it. Otherwise, it enters with that many charge counters on it.)
printings: PRM, VOC
text: Soulbond (You may pair this creature with another unpaired creature when either enters. They remain paired for as long as you control both of them.)
  As long as Thundering Mightmare is paired with another creature, each of those creatures has "Whenever an opponent casts a spell, put a +1/+1 counter on this creature."
type: Creature — Horse Spirit